T1004
Persistence
Winlogon.exe is a Windows component responsible for actions at logon/logoff as well as the secure attention sequence (SAS) triggered by Ctrl-Alt-Delete. Registry entries in <code>HKLM\Software\[Wow6432Node\]Microsoft\Windows NT\CurrentVersion\Winlogon\</code> and <code>HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\</code> are used to manage additional helper programs and functionalities that support Winlogon. (Citation: Cylance Reg Persistence Sept 2013)
Malicious modifications to these Registry keys may cause Winlogon to load and execute malicious DLLs and/or executables. Specifically, the following subkeys have been known to be possibly vulnerable to abuse: (Citation: Cylance Reg Persistence Sept 2013)
* Winlogon\Notify - points to notification package DLLs that handle Winlogon events
* Winlogon\Userinit - points to userinit.exe, the user initialization program executed when a user logs on
* Winlogon\Shell - points to explorer.exe, the system shell executed when a user logs on
Adversaries may take advantage of these features to repeatedly execute malicious code and establish Persistence.
T1013
PersistencePrivilege Escalation
A port monitor can be set through the (Citation: AddMonitor) API call to set a DLL to be loaded at startup. (Citation: AddMonitor) This DLL can be located in <code>C:\Windows\System32</code> and will be loaded by the print spooler service, spoolsv.exe, on boot. The spoolsv.exe process also runs under SYSTEM level permissions. (Citation: Bloxham) Alternatively, an arbitrary DLL can be loaded if permissions allow writing a fully-qualified pathname for that DLL to <code>HKLM\SYSTEM\CurrentControlSet\Control\Print\Monitors</code>.
The Registry key contains entries for the following:
* Local Port
* Standard TCP/IP Port
* USB Monitor
* WSD Port
Adversaries can use this technique to load malicious code at startup that will persist on system reboot and execute as SYSTEM.
T1015
PersistencePrivilege Escalation
Windows contains accessibility features that may be launched with a key combination before a user has logged in (for example, when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system.
Two common accessibility programs are <code>C:\Windows\System32\sethc.exe</code>, launched when the shift key is pressed five times and <code>C:\Windows\System32\utilman.exe</code>, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as "sticky keys", and has been used by adversaries for unauthenticated access through a remote desktop login screen. (Citation: FireEye Hikit Rootkit)
Depending on the version of Windows, an adversary may take advantage of these features in different ways because of code integrity enhancements. In newer versions of Windows, the replaced binary needs to be digitally signed for x64 systems, the binary must reside in <code>%systemdir%\</code>, and it must be protected by Windows File or Resource Protection (WFP/WRP). (Citation: DEFCON2016 Sticky Keys) The debugger method was likely discovered as a potential workaround because it does not require the corresponding accessibility feature binary to be replaced. Examples for both methods:
For simple binary replacement on Windows XP and later as well as and Windows Server 2003/R2 and later, for example, the program (e.g., <code>C:\Windows\System32\utilman.exe</code>) may be replaced with "cmd.exe" (or another program that provides backdoor access). Subsequently, pressing the appropriate key combination at the login screen while sitting at the keyboard or when connected over [Remote Desktop Protocol](https://attack.mitre.org/techniques/T1076) will cause the replaced file to be executed with SYSTEM privileges. (Citation: Tilbury 2014)
For the debugger method on Windows Vista and later as well as Windows Server 2008 and later, for example, a Registry key may be modified that configures "cmd.exe," or another program that provides backdoor access, as a "debugger" for the accessibility program (e.g., "utilman.exe"). After the Registry is modified, pressing the appropriate key combination at the login screen while at the keyboard or when connected with RDP will cause the "debugger" program to be executed with SYSTEM privileges. (Citation: Tilbury 2014)
Other accessibility features exist that may also be leveraged in a similar fashion: (Citation: DEFCON2016 Sticky Keys)
* On-Screen Keyboard: <code>C:\Windows\System32\osk.exe</code>
* Magnifier: <code>C:\Windows\System32\Magnify.exe</code>
* Narrator: <code>C:\Windows\System32\Narrator.exe</code>
* Display Switcher: <code>C:\Windows\System32\DisplaySwitch.exe</code>
* App Switcher: <code>C:\Windows\System32\AtBroker.exe</code>
T1019
Persistence
The BIOS (Basic Input/Output System) and The Unified Extensible Firmware Interface (UEFI) or Extensible Firmware Interface (EFI) are examples of system firmware that operate as the software interface between the operating system and hardware of a computer. (Citation: Wikipedia BIOS) (Citation: Wikipedia UEFI) (Citation: About UEFI)
System firmware like BIOS and (U)EFI underly the functionality of a computer and may be modified by an adversary to perform or assist in malicious activity. Capabilities exist to overwrite the system firmware, which may give sophisticated adversaries a means to install malicious firmware updates as a means of persistence on a system that may be difficult to detect.
T1023
Persistence
Shortcuts or symbolic links are ways of referencing other files or programs that will be opened or executed when the shortcut is clicked or executed by a system startup process. Adversaries could use shortcuts to execute their tools for persistence. They may create a new shortcut as a means of indirection that may use [Masquerading](https://attack.mitre.org/techniques/T1036) to look like a legitimate program. Adversaries could also edit the target path or entirely replace an existing shortcut so their tools will be executed instead of the intended legitimate program.
T1031
Persistence
Windows service configuration information, including the file path to the service's executable or recovery programs/commands, is stored in the Registry. Service configurations can be modified using utilities such as sc.exe and [Reg](https://attack.mitre.org/software/S0075).
Adversaries can modify an existing service to persist malware on a system by using system utilities or by using custom tools to interact with the Windows API. Use of existing services is a type of [Masquerading](https://attack.mitre.org/techniques/T1036) that may make detection analysis more challenging. Modifying existing services may interrupt their functionality or may enable services that are disabled or otherwise not commonly used.
Adversaries may also intentionally corrupt or kill services to execute malicious recovery programs/commands. (Citation: Twitter Service Recovery Nov 2017) (Citation: Microsoft Service Recovery Feb 2013)
T1037
PersistencePrivilege Escalation
Adversaries may use scripts automatically executed at boot or logon initialization to establish persistence.(Citation: Mandiant APT29 Eye Spy Email Nov 22)(Citation: Anomali Rocke March 2019) Initialization scripts can be used to perform administrative functions, which may often execute other programs or send information to an internal logging server. These scripts can vary based on operating system and whether applied locally or remotely.
Adversaries may use these scripts to maintain persistence on a single system. Depending on the access configuration of the logon scripts, either local credentials or an administrator account may be necessary.
An adversary may also be able to escalate their privileges since some boot or logon initialization scripts run with higher privileges.
T1037.001
PersistencePrivilege Escalation
Adversaries may use Windows logon scripts automatically executed at logon initialization to establish persistence. Windows allows logon scripts to be run whenever a specific user or group of users log into a system.(Citation: TechNet Logon Scripts) This is done via adding a path to a script to the <code>HKCU\Environment\UserInitMprLogonScript</code> Registry key.(Citation: Hexacorn Logon Scripts)
Adversaries may use these scripts to maintain persistence on a single system. Depending on the access configuration of the logon scripts, either local credentials or an administrator account may be necessary.
T1037.002
PersistencePrivilege Escalation
Adversaries may use a Login Hook to establish persistence executed upon user logon. A login hook is a plist file that points to a specific script to execute with root privileges upon user logon. The plist file is located in the <code>/Library/Preferences/com.apple.loginwindow.plist</code> file and can be modified using the <code>defaults</code> command-line utility. This behavior is the same for logout hooks where a script can be executed upon user logout. All hooks require administrator permissions to modify or create hooks.(Citation: Login Scripts Apple Dev)(Citation: LoginWindowScripts Apple Dev)
Adversaries can add or insert a path to a malicious script in the <code>com.apple.loginwindow.plist</code> file, using the <code>LoginHook</code> or <code>LogoutHook</code> key-value pair. The malicious script is executed upon the next user login. If a login hook already exists, adversaries can add additional commands to an existing login hook. There can be only one login and logout hook on a system at a time.(Citation: S1 macOs Persistence)(Citation: Wardle Persistence Chapter)
**Note:** Login hooks were deprecated in 10.11 version of macOS in favor of [Launch Daemon](https://attack.mitre.org/techniques/T1543/004) and [Launch Agent](https://attack.mitre.org/techniques/T1543/001).
T1037.003
PersistencePrivilege Escalation
Adversaries may use network logon scripts automatically executed at logon initialization to establish persistence. Network logon scripts can be assigned using Active Directory or Group Policy Objects.(Citation: Petri Logon Script AD) These logon scripts run with the privileges of the user they are assigned to. Depending on the systems within the network, initializing one of these scripts could apply to more than one or potentially all systems.
Adversaries may use these scripts to maintain persistence on a network. Depending on the access configuration of the logon scripts, either local credentials or an administrator account may be necessary.
T1037.004
PersistencePrivilege Escalation
Adversaries may establish persistence by modifying RC scripts, which are executed during a Unix-like system’s startup. These files allow system administrators to map and start custom services at startup for different run levels. RC scripts require root privileges to modify.
Adversaries may establish persistence by adding a malicious binary path or shell commands to <code>rc.local</code>, <code>rc.common</code>, and other RC scripts specific to the Unix-like distribution.(Citation: IranThreats Kittens Dec 2017)(Citation: Intezer HiddenWasp Map 2019) Upon reboot, the system executes the script's contents as root, resulting in persistence.
Adversary abuse of RC scripts is especially effective for lightweight Unix-like distributions using the root user as default, such as ESXi hypervisors, IoT, or embedded systems.(Citation: intezer-kaiji-malware) As ESXi servers store most system files in memory and therefore discard changes on shutdown, leveraging `/etc/rc.local.d/local.sh` is one of the few mechanisms for enabling persistence across reboots.(Citation: Juniper Networks ESXi Backdoor 2022)
Several Unix-like systems have moved to Systemd and deprecated the use of RC scripts. This is now a deprecated mechanism in macOS in favor of Launchd.(Citation: Apple Developer Doco Archive Launchd)(Citation: Startup Items) This technique can be used on Mac OS X Panther v10.3 and earlier versions which still execute the RC scripts.(Citation: Methods of Mac Malware Persistence) To maintain backwards compatibility some systems, such as Ubuntu, will execute the RC scripts if they exist with the correct file permissions.(Citation: Ubuntu Manpage systemd rc)
T1037.005
PersistencePrivilege Escalation
Adversaries may use startup items automatically executed at boot initialization to establish persistence. Startup items execute during the final phase of the boot process and contain shell scripts or other executable files along with configuration information used by the system to determine the execution order for all startup items.(Citation: Startup Items)
This is technically a deprecated technology (superseded by [Launch Daemon](https://attack.mitre.org/techniques/T1543/004)), and thus the appropriate folder, <code>/Library/StartupItems</code> isn’t guaranteed to exist on the system by default, but does appear to exist by default on macOS Sierra. A startup item is a directory whose executable and configuration property list (plist), <code>StartupParameters.plist</code>, reside in the top-level directory.
An adversary can create the appropriate folders/files in the StartupItems directory to register their own persistence mechanism.(Citation: Methods of Mac Malware Persistence) Additionally, since StartupItems run during the bootup phase of macOS, they will run as the elevated root user.
T1038
PersistencePrivilege EscalationStealth
Windows systems use a common method to look for required DLLs to load into a program. (Citation: Microsoft DLL Search) Adversaries may take advantage of the Windows DLL search order and programs that ambiguously specify DLLs to gain privilege escalation and persistence.
Adversaries may perform DLL preloading, also called binary planting attacks, (Citation: OWASP Binary Planting) by placing a malicious DLL with the same name as an ambiguously specified DLL in a location that Windows searches before the legitimate DLL. Often this location is the current working directory of the program. Remote DLL preloading attacks occur when a program sets its current directory to a remote location such as a Web share before loading a DLL. (Citation: Microsoft 2269637) Adversaries may use this behavior to cause the program to load a malicious DLL.
Adversaries may also directly modify the way a program loads DLLs by replacing an existing DLL or modifying a .manifest or .local redirection file, directory, or junction to cause the program to load a different DLL to maintain persistence or privilege escalation. (Citation: Microsoft DLL Redirection) (Citation: Microsoft Manifests) (Citation: Mandiant Search Order)
If a search order-vulnerable program is configured to run at a higher privilege level, then the adversary-controlled DLL that is loaded will also be executed at the higher level. In this case, the technique could be used for privilege escalation from user to administrator or SYSTEM or from administrator to SYSTEM, depending on the program.
Programs that fall victim to path hijacking may appear to behave normally because malicious DLLs may be configured to also load the legitimate DLLs they were meant to replace.
T1042
Persistence
When a file is opened, the default program used to open the file (also called the file association or handler) is checked. File association selections are stored in the Windows Registry and can be edited by users, administrators, or programs that have Registry access (Citation: Microsoft Change Default Programs) (Citation: Microsoft File Handlers) or by administrators using the built-in assoc utility. (Citation: Microsoft Assoc Oct 2017) Applications can modify the file association for a given file extension to call an arbitrary program when a file with the given extension is opened.
System file associations are listed under <code>HKEY_CLASSES_ROOT\.[extension]</code>, for example <code>HKEY_CLASSES_ROOT\.txt</code>. The entries point to a handler for that extension located at <code>HKEY_CLASSES_ROOT\[handler]</code>. The various commands are then listed as subkeys underneath the shell key at <code>HKEY_CLASSES_ROOT\[handler]\shell\[action]\command</code>. For example:
* <code>HKEY_CLASSES_ROOT\txtfile\shell\open\command</code>
* <code>HKEY_CLASSES_ROOT\txtfile\shell\print\command</code>
* <code>HKEY_CLASSES_ROOT\txtfile\shell\printto\command</code>
The values of the keys listed are commands that are executed when the handler opens the file extension. Adversaries can modify these values to continually execute arbitrary commands. (Citation: TrendMicro TROJ-FAKEAV OCT 2012)
T1044
PersistencePrivilege Escalation
Processes may automatically execute specific binaries as part of their functionality or to perform other actions. If the permissions on the file system directory containing a target binary, or permissions on the binary itself, are improperly set, then the target binary may be overwritten with another binary using user-level permissions and executed by the original process. If the original process and thread are running under a higher permissions level, then the replaced binary will also execute under higher-level permissions, which could include SYSTEM.
Adversaries may use this technique to replace legitimate binaries with malicious ones as a means of executing code at a higher permissions level. If the executing process is set to run at a specific time or during a certain event (e.g., system bootup) then this technique can also be used for persistence.
### Services
Manipulation of Windows service binaries is one variation of this technique. Adversaries may replace a legitimate service executable with their own executable to gain persistence and/or privilege escalation to the account context the service is set to execute under (local/domain account, SYSTEM, LocalService, or NetworkService). Once the service is started, either directly by the user (if appropriate access is available) or through some other means, such as a system restart if the service starts on bootup, the replaced executable will run instead of the original service executable.
### Executable Installers
Another variation of this technique can be performed by taking advantage of a weakness that is common in executable, self-extracting installers. During the installation process, it is common for installers to use a subdirectory within the <code>%TEMP%</code> directory to unpack binaries such as DLLs, EXEs, or other payloads. When installers create subdirectories and files they often do not set appropriate permissions to restrict write access, which allows for execution of untrusted code placed in the subdirectories or overwriting of binaries used in the installation process. This behavior is related to and may take advantage of [DLL Search Order Hijacking](https://attack.mitre.org/techniques/T1038). Some installers may also require elevated privileges that will result in privilege escalation when executing adversary controlled code. This behavior is related to [Bypass User Account Control](https://attack.mitre.org/techniques/T1088). Several examples of this weakness in existing common installers have been reported to software vendors. (Citation: Mozilla Firefox Installer DLL Hijack) (Citation: Seclists Kanthak 7zip Installer)
T1050
PersistencePrivilege Escalation
When operating systems boot up, they can start programs or applications called services that perform background system functions. (Citation: TechNet Services) A service's configuration information, including the file path to the service's executable, is stored in the Windows Registry.
Adversaries may install a new service that can be configured to execute at startup by using utilities to interact with services or by directly modifying the Registry. The service name may be disguised by using a name from a related operating system or benign software with [Masquerading](https://attack.mitre.org/techniques/T1036). Services may be created with administrator privileges but are executed under SYSTEM privileges, so an adversary may also use a service to escalate privileges from administrator to SYSTEM. Adversaries may also directly start services through [Service Execution](https://attack.mitre.org/techniques/T1035).
T1053
ExecutionPersistencePrivilege Escalation
Adversaries may abuse task scheduling functionality to facilitate initial or recurring execution of malicious code. Utilities exist within all major operating systems to schedule programs or scripts to be executed at a specified date and time. A task can also be scheduled on a remote system, provided the proper authentication is met (ex: RPC and file and printer sharing in Windows environments). Scheduling a task on a remote system typically may require being a member of an admin or otherwise privileged group on the remote system.(Citation: TechNet Task Scheduler Security)
Adversaries may use task scheduling to execute programs at system startup or on a scheduled basis for persistence. These mechanisms can also be abused to run a process under the context of a specified account (such as one with elevated permissions/privileges). Similar to [System Binary Proxy Execution](https://attack.mitre.org/techniques/T1218), adversaries have also abused task scheduling to potentially mask one-time execution under a trusted system process.(Citation: ProofPoint Serpent)
T1053.001
ExecutionPersistencePrivilege Escalation
Adversaries may abuse the [at](https://attack.mitre.org/software/S0110) utility to perform task scheduling for initial, recurring, or future execution of malicious code. The [at](https://attack.mitre.org/software/S0110) command within Linux operating systems enables administrators to schedule tasks.(Citation: Kifarunix - Task Scheduling in Linux)
An adversary may use [at](https://attack.mitre.org/software/S0110) in Linux environments to execute programs at system startup or on a scheduled basis for persistence. [at](https://attack.mitre.org/software/S0110) can also be abused to conduct remote Execution as part of Lateral Movement and or to run a process under the context of a specified account.
Adversaries may also abuse [at](https://attack.mitre.org/software/S0110) to break out of restricted environments by using a task to spawn an interactive system shell or to run system commands. Similarly, [at](https://attack.mitre.org/software/S0110) may also be used for [Privilege Escalation](https://attack.mitre.org/tactics/TA0004) if the binary is allowed to run as superuser via <code>sudo</code>.(Citation: GTFObins at)
T1053.002
ExecutionPersistencePrivilege Escalation
Adversaries may abuse the [at](https://attack.mitre.org/software/S0110) utility to perform task scheduling for initial or recurring execution of malicious code. The [at](https://attack.mitre.org/software/S0110) utility exists as an executable within Windows, Linux, and macOS for scheduling tasks at a specified time and date. Although deprecated in favor of [Scheduled Task](https://attack.mitre.org/techniques/T1053/005)'s [schtasks](https://attack.mitre.org/software/S0111) in Windows environments, using [at](https://attack.mitre.org/software/S0110) requires that the Task Scheduler service be running, and the user to be logged on as a member of the local Administrators group. In addition to explicitly running the `at` command, adversaries may also schedule a task with [at](https://attack.mitre.org/software/S0110) by directly leveraging the [Windows Management Instrumentation](https://attack.mitre.org/techniques/T1047) `Win32_ScheduledJob` WMI class.(Citation: Malicious Life by Cybereason)
On Linux and macOS, [at](https://attack.mitre.org/software/S0110) may be invoked by the superuser as well as any users added to the <code>at.allow</code> file. If the <code>at.allow</code> file does not exist, the <code>at.deny</code> file is checked. Every username not listed in <code>at.deny</code> is allowed to invoke [at](https://attack.mitre.org/software/S0110). If the <code>at.deny</code> exists and is empty, global use of [at](https://attack.mitre.org/software/S0110) is permitted. If neither file exists (which is often the baseline) only the superuser is allowed to use [at](https://attack.mitre.org/software/S0110).(Citation: Linux at)
Adversaries may use [at](https://attack.mitre.org/software/S0110) to execute programs at system startup or on a scheduled basis for [Persistence](https://attack.mitre.org/tactics/TA0003). [at](https://attack.mitre.org/software/S0110) can also be abused to conduct remote [Execution](https://attack.mitre.org/tactics/TA0002) as part of [Lateral Movement](https://attack.mitre.org/tactics/TA0008) and/or to run a process under the context of a specified account (such as SYSTEM).
In Linux environments, adversaries may also abuse [at](https://attack.mitre.org/software/S0110) to break out of restricted environments by using a task to spawn an interactive system shell or to run system commands. Similarly, [at](https://attack.mitre.org/software/S0110) may also be used for [Privilege Escalation](https://attack.mitre.org/tactics/TA0004) if the binary is allowed to run as superuser via <code>sudo</code>.(Citation: GTFObins at)
T1053.003
ExecutionPersistencePrivilege Escalation
Adversaries may abuse the <code>cron</code> utility to perform task scheduling for initial or recurring execution of malicious code.(Citation: 20 macOS Common Tools and Techniques) The <code>cron</code> utility is a time-based job scheduler for Unix-like operating systems. The <code> crontab</code> file contains the schedule of cron entries to be run and the specified times for execution. Any <code>crontab</code> files are stored in operating system-specific file paths.
An adversary may use <code>cron</code> in Linux or Unix environments to execute programs at system startup or on a scheduled basis for [Persistence](https://attack.mitre.org/tactics/TA0003). In ESXi environments, cron jobs must be created directly via the crontab file (e.g., `/var/spool/cron/crontabs/root`).(Citation: CloudSEK ESXiArgs 2023)
T1053.005
ExecutionPersistencePrivilege Escalation
Adversaries may abuse the Windows Task Scheduler to perform task scheduling for initial or recurring execution of malicious code. There are multiple ways to access the Task Scheduler in Windows. The [schtasks](https://attack.mitre.org/software/S0111) utility can be run directly on the command line, or the Task Scheduler can be opened through the GUI within the Administrator Tools section of the Control Panel.(Citation: Stack Overflow) In some cases, adversaries have used a .NET wrapper for the Windows Task Scheduler, and alternatively, adversaries have used the Windows netapi32 library and [Windows Management Instrumentation](https://attack.mitre.org/techniques/T1047) (WMI) to create a scheduled task. Adversaries may also utilize the Powershell Cmdlet `Invoke-CimMethod`, which leverages WMI class `PS_ScheduledTask` to create a scheduled task via an XML path.(Citation: Red Canary - Atomic Red Team)
An adversary may use Windows Task Scheduler to execute programs at system startup or on a scheduled basis for persistence. The Windows Task Scheduler can also be abused to conduct remote Execution as part of Lateral Movement and/or to run a process under the context of a specified account (such as SYSTEM). Similar to [System Binary Proxy Execution](https://attack.mitre.org/techniques/T1218), adversaries have also abused the Windows Task Scheduler to potentially mask one-time execution under signed/trusted system processes.(Citation: ProofPoint Serpent)
Adversaries may also create "hidden" scheduled tasks (i.e. [Hide Artifacts](https://attack.mitre.org/techniques/T1564)) that may not be visible to defender tools and manual queries used to enumerate tasks. Specifically, an adversary may hide a task from `schtasks /query` and the Task Scheduler by deleting the associated Security Descriptor (SD) registry value (where deletion of this value must be completed using SYSTEM permissions).(Citation: SigmaHQ)(Citation: Tarrask scheduled task) Adversaries may also employ alternate methods to hide tasks, such as altering the metadata (e.g., `Index` value) within associated registry keys.(Citation: Defending Against Scheduled Task Attacks in Windows Environments)
T1053.006
ExecutionPersistencePrivilege Escalation
Adversaries may abuse systemd timers to perform task scheduling for initial or recurring execution of malicious code. Systemd timers are unit files with file extension <code>.timer</code> that control services. Timers can be set to run on a calendar event or after a time span relative to a starting point. They can be used as an alternative to [Cron](https://attack.mitre.org/techniques/T1053/003) in Linux environments.(Citation: archlinux Systemd Timers Aug 2020) Systemd timers may be activated remotely via the <code>systemctl</code> command line utility, which operates over [SSH](https://attack.mitre.org/techniques/T1021/004).(Citation: Systemd Remote Control)
Each <code>.timer</code> file must have a corresponding <code>.service</code> file with the same name, e.g., <code>example.timer</code> and <code>example.service</code>. <code>.service</code> files are [Systemd Service](https://attack.mitre.org/techniques/T1543/002) unit files that are managed by the systemd system and service manager.(Citation: Linux man-pages: systemd January 2014) Privileged timers are written to <code>/etc/systemd/system/</code> and <code>/usr/lib/systemd/system</code> while user level are written to <code>~/.config/systemd/user/</code>.
An adversary may use systemd timers to execute malicious code at system startup or on a scheduled basis for persistence.(Citation: Arch Linux Package Systemd Compromise BleepingComputer 10JUL2018)(Citation: gist Arch package compromise 10JUL2018)(Citation: acroread package compromised Arch Linux Mail 8JUL2018) Timers installed using privileged paths may be used to maintain root level persistence. Adversaries may also install user level timers to achieve user level persistence.(Citation: Falcon Sandbox smp: 28553b3a9d)
T1053.007
ExecutionPersistencePrivilege Escalation
Adversaries may abuse task scheduling functionality provided by container orchestration tools such as Kubernetes to schedule deployment of containers configured to execute malicious code. Container orchestration jobs run these automated tasks at a specific date and time, similar to cron jobs on a Linux system. Deployments of this type can also be configured to maintain a quantity of containers over time, automating the process of maintaining persistence within a cluster.
In Kubernetes, a CronJob may be used to schedule a Job that runs one or more containers to perform specific tasks.(Citation: Kubernetes Jobs)(Citation: Kubernetes CronJob) An adversary therefore may utilize a CronJob to schedule deployment of a Job that executes malicious code in various nodes within a cluster.(Citation: Threat Matrix for Kubernetes)
T1058
PersistencePrivilege Escalation
Windows stores local service configuration information in the Registry under <code>HKLM\SYSTEM\CurrentControlSet\Services</code>. The information stored under a service's Registry keys can be manipulated to modify a service's execution parameters through tools such as the service controller, sc.exe, [PowerShell](https://attack.mitre.org/techniques/T1086), or [Reg](https://attack.mitre.org/software/S0075). Access to Registry keys is controlled through Access Control Lists and permissions. (Citation: MSDN Registry Key Security)
If the permissions for users and groups are not properly set and allow access to the Registry keys for a service, then adversaries can change the service binPath/ImagePath to point to a different executable under their control. When the service starts or is restarted, then the adversary-controlled program will execute, allowing the adversary to gain persistence and/or privilege escalation to the account context the service is set to execute under (local/domain account, SYSTEM, LocalService, or NetworkService).
Adversaries may also alter Registry keys associated with service failure parameters (such as <code>FailureCommand</code>) that may be executed in an elevated context anytime the service fails or is intentionally corrupted.(Citation: TrustedSignal Service Failure)(Citation: Twitter Service Recovery Nov 2017)
T1060
Persistence
Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. Adding an entry to the "run keys" in the Registry or startup folder will cause the program referenced to be executed when a user logs in. (Citation: Microsoft Run Key) These programs will be executed under the context of the user and will have the account's associated permissions level.
Placing a program within a startup folder will cause that program to execute when a user logs in. There is a startup folder location for individual user accounts as well as a system-wide startup folder that will be checked regardless of which user account logs in.
The startup folder path for the current user is:
* <code>C:\Users\[Username]\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup</code>
The startup folder path for all users is:
* <code>C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp</code>
The following run keys are created by default on Windows systems:
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce</code>
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run</code>
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce</code>
The <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnceEx</code> is also available but is not created by default on Windows Vista and newer. Registry run key entries can reference programs directly or list them as a dependency. (Citation: Microsoft RunOnceEx APR 2018) For example, it is possible to load a DLL at logon using a "Depend" key with RunOnceEx: <code>reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnceEx\0001\Depend /v 1 /d "C:\temp\evil[.]dll"</code> (Citation: Oddvar Moe RunOnceEx Mar 2018)
The following Registry keys can be used to set startup folder items for persistence:
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders</code>
* <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders</code>
* <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders</code>
The following Registry keys can control automatic startup of services during boot:
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServicesOnce</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServicesOnce</code>
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServices</code>
Using policy settings to specify startup programs creates corresponding values in either of two Registry keys:
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run</code>
The Winlogon key controls actions that occur when a user logs on to a computer running Windows 7. Most of these actions are under the control of the operating system, but you can also add custom actions here. The <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit</code> and <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell</code> subkeys can automatically launch programs.
Programs listed in the load value of the registry key <code>HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows</code> run when any user logs on.
By default, the multistring BootExecute value of the registry key <code>HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager</code> is set to autocheck autochk *. This value causes Windows, at startup, to check the file-system integrity of the hard disks if the system has been shut down abnormally. Adversaries can add other programs or processes to this registry value which will automatically launch at boot.
Adversaries can use these configuration locations to execute malware, such as remote access tools, to maintain persistence through system reboots. Adversaries may also use [Masquerading](https://attack.mitre.org/techniques/T1036) to make the Registry entries look as if they are associated with legitimate programs.
T1067
Persistence
A bootkit is a malware variant that modifies the boot sectors of a hard drive, including the Master Boot Record (MBR) and Volume Boot Record (VBR). (Citation: MTrends 2016)
Adversaries may use bootkits to persist on systems at a layer below the operating system, which may make it difficult to perform full remediation unless an organization suspects one was used and can act accordingly.
### Master Boot Record
The MBR is the section of disk that is first loaded after completing hardware initialization by the BIOS. It is the location of the boot loader. An adversary who has raw access to the boot drive may overwrite this area, diverting execution during startup from the normal boot loader to adversary code. (Citation: Lau 2011)
### Volume Boot Record
The MBR passes control of the boot process to the VBR. Similar to the case of MBR, an adversary who has raw access to the boot drive may overwrite the VBR to divert execution during startup to adversary code.
T1078
Initial AccessPersistencePrivilege EscalationStealth
Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop.(Citation: volexity_0day_sophos_FW) Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network. Adversaries may choose not to use malware or tools in conjunction with the legitimate access those credentials provide to make it harder to detect their presence.
In some cases, adversaries may abuse inactive accounts: for example, those belonging to individuals who are no longer part of an organization. Using these accounts may allow the adversary to evade detection, as the original account user will not be present to identify any anomalous activity taking place on their account.(Citation: CISA MFA PrintNightmare)
The overlap of permissions for local, domain, and cloud accounts across a network of systems is of concern because the adversary may be able to pivot across accounts and systems to reach a high level of access (i.e., domain or enterprise administrator) to bypass access controls set within the enterprise.(Citation: TechNet Credential Theft)
T1078.001
Initial AccessPersistencePrivilege EscalationStealth
Adversaries may obtain and abuse credentials of a default account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Default accounts are those that are built-into an OS, such as the Guest or Administrator accounts on Windows systems. Default accounts also include default factory/provider set accounts on other types of systems, software, or devices, including the root user account in AWS, the root user account in ESXi, and the default service account in Kubernetes.(Citation: Microsoft Local Accounts Feb 2019)(Citation: AWS Root User)(Citation: Threat Matrix for Kubernetes)
Default accounts are not limited to client machines; rather, they also include accounts that are preset for equipment such as network devices and computer applications, whether they are internal, open source, or commercial. Appliances that come preset with a username and password combination pose a serious threat to organizations that do not change it post installation, as they are easy targets for an adversary. Similarly, adversaries may also utilize publicly disclosed or stolen [Private Keys](https://attack.mitre.org/techniques/T1552/004) or credential materials to legitimately connect to remote environments via [Remote Services](https://attack.mitre.org/techniques/T1021).(Citation: Metasploit SSH Module)
Default accounts may be created on a system after initial setup by connecting or integrating it with another application. For example, when an ESXi server is connected to a vCenter server, a default privileged account called `vpxuser` is created on the ESXi server. If a threat actor is able to compromise this account’s credentials (for example, via [Exploitation for Credential Access](https://attack.mitre.org/techniques/T1212) on the vCenter host), they will then have access to the ESXi server.(Citation: Google Cloud Threat Intelligence VMWare ESXi Zero-Day 2023)(Citation: Pentera vCenter Information Disclosure)
T1078.002
Initial AccessPersistencePrivilege EscalationStealth
Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.(Citation: TechNet Credential Theft) Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.(Citation: Microsoft AD Accounts)
Adversaries may compromise domain accounts, some with a high level of privileges, through various means such as [OS Credential Dumping](https://attack.mitre.org/techniques/T1003) or password reuse, allowing access to privileged resources of the domain.
T1078.003
Initial AccessPersistencePrivilege EscalationStealth
Adversaries may obtain and abuse credentials of a local account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Local accounts are those configured by an organization for use by users, remote support, services, or for administration on a single system or service.
Local Accounts may also be abused to elevate privileges and harvest credentials through [OS Credential Dumping](https://attack.mitre.org/techniques/T1003). Password reuse may allow the abuse of local accounts across a set of machines on a network for the purposes of Privilege Escalation and Lateral Movement.
T1078.004
Initial AccessPersistencePrivilege EscalationStealth
Valid accounts in cloud environments may allow adversaries to perform actions to achieve Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. Cloud Accounts can exist solely in the cloud; alternatively, they may be hybrid-joined between on-premises systems and the cloud through syncing or federation with other identity sources such as Windows Active Directory.(Citation: AWS Identity Federation)(Citation: Google Federating GC)(Citation: Microsoft Deploying AD Federation)
Service or user accounts may be targeted by adversaries through [Brute Force](https://attack.mitre.org/techniques/T1110), [Phishing](https://attack.mitre.org/techniques/T1566), or various other means to gain access to the environment. Federated or synced accounts may be a pathway for the adversary to affect both on-premises systems and cloud environments - for example, by leveraging shared credentials to log onto [Remote Services](https://attack.mitre.org/techniques/T1021). High privileged cloud accounts, whether federated, synced, or cloud-only, may also allow pivoting to on-premises environments by leveraging SaaS-based [Software Deployment Tools](https://attack.mitre.org/techniques/T1072) to run commands on hybrid-joined devices.
An adversary may create long lasting [Additional Cloud Credentials](https://attack.mitre.org/techniques/T1098/001) on a compromised cloud account to maintain persistence in the environment. Such credentials may also be used to bypass security controls such as multi-factor authentication.
Cloud accounts may also be able to assume [Temporary Elevated Cloud Access](https://attack.mitre.org/techniques/T1548/005) or other privileges through various means within the environment. Misconfigurations in role assignments or role assumption policies may allow an adversary to use these mechanisms to leverage permissions outside the intended scope of the account. Such over privileged accounts may be used to harvest sensitive data from online storage accounts and databases through [Cloud API](https://attack.mitre.org/techniques/T1059/009) or other methods. For example, in Azure environments, adversaries may target Azure Managed Identities, which allow associated Azure resources to request access tokens. By compromising a resource with an attached Managed Identity, such as an Azure VM, adversaries may be able to [Steal Application Access Token](https://attack.mitre.org/techniques/T1528)s to move laterally across the cloud environment.(Citation: SpecterOps Managed Identity 2022)
T1084
Persistence
Windows Management Instrumentation (WMI) can be used to install event filters, providers, consumers, and bindings that execute code when a defined event occurs. Adversaries may use the capabilities of WMI to subscribe to an event and execute arbitrary code when that event occurs, providing persistence on a system. Adversaries may attempt to evade detection of this technique by compiling WMI scripts into Windows Management Object (MOF) files (.mof extension). (Citation: Dell WMI Persistence) Examples of events that may be subscribed to are the wall clock time or the computer's uptime. (Citation: Kazanciyan 2014) Several threat groups have reportedly used this technique to maintain persistence. (Citation: Mandiant M-Trends 2015)
T1098
PersistencePrivilege Escalation
Adversaries may manipulate accounts to maintain and/or elevate access to victim systems. Account manipulation may consist of any action that preserves or modifies adversary access to a compromised account, such as modifying credentials or permission groups.(Citation: FireEye SMOKEDHAM June 2021) These actions could also include account activity designed to subvert security policies, such as performing iterative password updates to bypass password duration policies and preserve the life of compromised credentials.
In order to create or manipulate accounts, the adversary must already have sufficient permissions on systems or the domain. However, account manipulation may also lead to privilege escalation where modifications grant access to additional roles, permissions, or higher-privileged [Valid Accounts](https://attack.mitre.org/techniques/T1078).
T1098.001
PersistencePrivilege Escalation
Adversaries may add adversary-controlled credentials to a cloud account to maintain persistent access to victim accounts and instances within the environment.
For example, adversaries may add credentials for Service Principals and Applications in addition to existing legitimate credentials in Azure / Entra ID.(Citation: Microsoft SolarWinds Customer Guidance)(Citation: Blue Cloud of Death)(Citation: Blue Cloud of Death Video) These credentials include both x509 keys and passwords.(Citation: Microsoft SolarWinds Customer Guidance) With sufficient permissions, there are a variety of ways to add credentials including the Azure Portal, Azure command line interface, and Azure or Az PowerShell modules.(Citation: Demystifying Azure AD Service Principals)
In infrastructure-as-a-service (IaaS) environments, after gaining access through [Cloud Accounts](https://attack.mitre.org/techniques/T1078/004), adversaries may generate or import their own SSH keys using either the <code>CreateKeyPair</code> or <code>ImportKeyPair</code> API in AWS or the <code>gcloud compute os-login ssh-keys add</code> command in GCP.(Citation: GCP SSH Key Add) This allows persistent access to instances within the cloud environment without further usage of the compromised cloud accounts.(Citation: Expel IO Evil in AWS)(Citation: Expel Behind the Scenes)
Adversaries may also use the <code>CreateAccessKey</code> API in AWS or the <code>gcloud iam service-accounts keys create</code> command in GCP to add access keys to an account. Alternatively, they may use the <code>CreateLoginProfile</code> API in AWS to add a password that can be used to log into the AWS Management Console for [Cloud Service Dashboard](https://attack.mitre.org/techniques/T1538).(Citation: Permiso Scattered Spider 2023)(Citation: Lacework AI Resource Hijacking 2024) If the target account has different permissions from the requesting account, the adversary may also be able to escalate their privileges in the environment (i.e. [Cloud Accounts](https://attack.mitre.org/techniques/T1078/004)).(Citation: Rhino Security Labs AWS Privilege Escalation)(Citation: Sysdig ScarletEel 2.0) For example, in Entra ID environments, an adversary with the Application Administrator role can add a new set of credentials to their application's service principal. In doing so the adversary would be able to access the service principal’s roles and permissions, which may be different from those of the Application Administrator.(Citation: SpecterOps Azure Privilege Escalation)
In AWS environments, adversaries with the appropriate permissions may also use the `sts:GetFederationToken` API call to create a temporary set of credentials to [Forge Web Credentials](https://attack.mitre.org/techniques/T1606) tied to the permissions of the original user account. These temporary credentials may remain valid for the duration of their lifetime even if the original account’s API credentials are deactivated.(Citation: Crowdstrike AWS User Federation Persistence)
In Entra ID environments with the app password feature enabled, adversaries may be able to add an app password to a user account.(Citation: Mandiant APT42-untangling) As app passwords are intended to be used with legacy devices that do not support multi-factor authentication (MFA), adding an app password can allow an adversary to bypass MFA requirements. Additionally, app passwords may remain valid even if the user’s primary password is reset.(Citation: Microsoft Entra ID App Passwords)
T1098.002
PersistencePrivilege Escalation
Adversaries may grant additional permission levels to maintain persistent access to an adversary-controlled email account.
For example, the <code>Add-MailboxPermission</code> [PowerShell](https://attack.mitre.org/techniques/T1059/001) cmdlet, available in on-premises Exchange and in the cloud-based service Office 365, adds permissions to a mailbox.(Citation: Microsoft - Add-MailboxPermission)(Citation: FireEye APT35 2018)(Citation: Crowdstrike Hiding in Plain Sight 2018) In Google Workspace, delegation can be enabled via the Google Admin console and users can delegate accounts via their Gmail settings.(Citation: Gmail Delegation)(Citation: Google Ensuring Your Information is Safe)
Adversaries may also assign mailbox folder permissions through individual folder permissions or roles. In Office 365 environments, adversaries may assign the Default or Anonymous user permissions or roles to the Top of Information Store (root), Inbox, or other mailbox folders. By assigning one or both user permissions to a folder, the adversary can utilize any other account in the tenant to maintain persistence to the target user’s mail folders.(Citation: Mandiant Defend UNC2452 White Paper)
This may be used in persistent threat incidents as well as BEC (Business Email Compromise) incidents where an adversary can add [Additional Cloud Roles](https://attack.mitre.org/techniques/T1098/003) to the accounts they wish to compromise. This may further enable use of additional techniques for gaining access to systems. For example, compromised business accounts are often used to send messages to other accounts in the network of the target business while creating inbox rules (ex: [Internal Spearphishing](https://attack.mitre.org/techniques/T1534)), so the messages evade spam/phishing detection mechanisms.(Citation: Bienstock, D. - Defending O365 - 2019)
T1098.003
PersistencePrivilege Escalation
An adversary may add additional roles or permissions to an adversary-controlled cloud account to maintain persistent access to a tenant. For example, adversaries may update IAM policies in cloud-based environments or add a new global administrator in Office 365 environments.(Citation: AWS IAM Policies and Permissions)(Citation: Google Cloud IAM Policies)(Citation: Microsoft Support O365 Add Another Admin, October 2019)(Citation: Microsoft O365 Admin Roles) With sufficient permissions, a compromised account can gain almost unlimited access to data and settings (including the ability to reset the passwords of other admins).(Citation: Expel AWS Attacker)(Citation: Microsoft O365 Admin Roles)
This account modification may immediately follow [Create Account](https://attack.mitre.org/techniques/T1136) or other malicious account activity. Adversaries may also modify existing [Valid Accounts](https://attack.mitre.org/techniques/T1078) that they have compromised. This could lead to privilege escalation, particularly if the roles added allow for lateral movement to additional accounts.
For example, in AWS environments, an adversary with appropriate permissions may be able to use the <code>CreatePolicyVersion</code> API to define a new version of an IAM policy or the <code>AttachUserPolicy</code> API to attach an IAM policy with additional or distinct permissions to a compromised user account.(Citation: Rhino Security Labs AWS Privilege Escalation)
In some cases, adversaries may add roles to adversary-controlled accounts outside the victim cloud tenant. This allows these external accounts to perform actions inside the victim tenant without requiring the adversary to [Create Account](https://attack.mitre.org/techniques/T1136) or modify a victim-owned account.(Citation: Invictus IR DangerDev 2024)
T1098.004
PersistencePrivilege Escalation
Adversaries may modify the SSH <code>authorized_keys</code> file to maintain persistence on a victim host. Linux distributions, macOS, and ESXi hypervisors commonly use key-based authentication to secure the authentication process of SSH sessions for remote management. The <code>authorized_keys</code> file in SSH specifies the SSH keys that can be used for logging into the user account for which the file is configured. This file is usually found in the user's home directory under <code><user-home>/.ssh/authorized_keys</code> (or, on ESXi, `/etc/ssh/keys-<username>/authorized_keys`).(Citation: SSH Authorized Keys) Users may edit the system’s SSH config file to modify the directives `PubkeyAuthentication` and `RSAAuthentication` to the value `yes` to ensure public key and RSA authentication are enabled, as well as modify the directive `PermitRootLogin` to the value `yes` to enable root authentication via SSH.(Citation: Broadcom ESXi SSH) The SSH config file is usually located under <code>/etc/ssh/sshd_config</code>.
Adversaries may modify SSH <code>authorized_keys</code> files directly with scripts or shell commands to add their own adversary-supplied public keys. In cloud environments, adversaries may be able to modify the SSH authorized_keys file of a particular virtual machine via the command line interface or rest API. For example, by using the Google Cloud CLI’s “add-metadata” command an adversary may add SSH keys to a user account.(Citation: Google Cloud Add Metadata)(Citation: Google Cloud Privilege Escalation) Similarly, in Azure, an adversary may update the authorized_keys file of a virtual machine via a PATCH request to the API.(Citation: Azure Update Virtual Machines) This ensures that an adversary possessing the corresponding private key may log in as an existing user via SSH.(Citation: Venafi SSH Key Abuse)(Citation: Cybereason Linux Exim Worm) It may also lead to privilege escalation where the virtual machine or instance has distinct permissions from the requesting user.
Where authorized_keys files are modified via cloud APIs or command line interfaces, an adversary may achieve privilege escalation on the target virtual machine if they add a key to a higher-privileged user.
SSH keys can also be added to accounts on network devices, such as with the `ip ssh pubkey-chain` [Network Device CLI](https://attack.mitre.org/techniques/T1059/008) command.(Citation: cisco_ip_ssh_pubkey_ch_cmd)
T1098.005
PersistencePrivilege Escalation
Adversaries may register a device to an adversary-controlled account. Devices may be registered in a multifactor authentication (MFA) system, which handles authentication to the network, or in a device management system, which handles device access and compliance.
MFA systems, such as Duo or Okta, allow users to associate devices with their accounts in order to complete MFA requirements. An adversary that compromises a user’s credentials may enroll a new device in order to bypass initial MFA requirements and gain persistent access to a network.(Citation: CISA MFA PrintNightmare)(Citation: DarkReading FireEye SolarWinds) In some cases, the MFA self-enrollment process may require only a username and password to enroll the account's first device or to enroll a device to an inactive account.(Citation: Mandiant APT29 Microsoft 365 2022)
Similarly, an adversary with existing access to a network may register a device or a virtual machine to Entra ID and/or its device management system, Microsoft Intune, in order to access sensitive data or resources while bypassing conditional access policies.(Citation: AADInternals - Device Registration)(Citation: AADInternals - Conditional Access Bypass)(Citation: Microsoft DEV-0537)(Citation: Expel Atlas Lion 2025)
Devices registered in Entra ID may be able to conduct [Internal Spearphishing](https://attack.mitre.org/techniques/T1534) campaigns via intra-organizational emails, which are less likely to be treated as suspicious by the email client.(Citation: Microsoft - Device Registration) Additionally, an adversary may be able to perform a [Service Exhaustion Flood](https://attack.mitre.org/techniques/T1499/002) on an Entra ID tenant by registering a large number of devices.(Citation: AADInternals - BPRT)
T1098.006
PersistencePrivilege Escalation
An adversary may add additional roles or permissions to an adversary-controlled user or service account to maintain persistent access to a container orchestration system. For example, an adversary with sufficient permissions may create a RoleBinding or a ClusterRoleBinding to bind a Role or ClusterRole to a Kubernetes account.(Citation: Kubernetes RBAC)(Citation: Aquasec Kubernetes Attack 2023) Where attribute-based access control (ABAC) is in use, an adversary with sufficient permissions may modify a Kubernetes ABAC policy to give the target account additional permissions.(Citation: Kuberentes ABAC)
This account modification may immediately follow [Create Account](https://attack.mitre.org/techniques/T1136) or other malicious account activity. Adversaries may also modify existing [Valid Accounts](https://attack.mitre.org/techniques/T1078) that they have compromised.
Note that where container orchestration systems are deployed in cloud environments, as with Google Kubernetes Engine, Amazon Elastic Kubernetes Service, and Azure Kubernetes Service, cloud-based role-based access control (RBAC) assignments or ABAC policies can often be used in place of or in addition to local permission assignments.(Citation: Google Cloud Kubernetes IAM)(Citation: AWS EKS IAM Roles for Service Accounts)(Citation: Microsoft Azure Kubernetes Service Service Accounts) In these cases, this technique may be used in conjunction with [Additional Cloud Roles](https://attack.mitre.org/techniques/T1098/003).
T1098.007
PersistencePrivilege Escalation
An adversary may add additional local or domain groups to an adversary-controlled account to maintain persistent access to a system or domain.
On Windows, accounts may use the `net localgroup` and `net group` commands to add existing users to local and domain groups.(Citation: Microsoft Net Localgroup)(Citation: Microsoft Net Group) On Linux, adversaries may use the `usermod` command for the same purpose.(Citation: Linux Usermod)
For example, accounts may be added to the local administrators group on Windows devices to maintain elevated privileges. They may also be added to the Remote Desktop Users group, which allows them to leverage [Remote Desktop Protocol](https://attack.mitre.org/techniques/T1021/001) to log into the endpoints in the future.(Citation: Microsoft RDP Logons) Adversaries may also add accounts to VPN user groups to gain future persistence on the network.(Citation: Cyber Security News) On Linux, accounts may be added to the sudoers group, allowing them to persistently leverage [Sudo and Sudo Caching](https://attack.mitre.org/techniques/T1548/003) for elevated privileges.
In Windows environments, machine accounts may also be added to domain groups. This allows the local SYSTEM account to gain privileges on the domain.(Citation: RootDSE AD Detection 2022)
T1100
PersistencePrivilege Escalation
A Web shell is a Web script that is placed on an openly accessible Web server to allow an adversary to use the Web server as a gateway into a network. A Web shell may provide a set of functions to execute or a command-line interface on the system that hosts the Web server. In addition to a server-side script, a Web shell may have a client interface program that is used to talk to the Web server (see, for example, China Chopper Web shell client). (Citation: Lee 2013)
Web shells may serve as [Redundant Access](https://attack.mitre.org/techniques/T1108) or as a persistence mechanism in case an adversary's primary access methods are detected and removed.
T1101
Persistence
Windows Security Support Provider (SSP) DLLs are loaded into the Local Security Authority (LSA) process at system start. Once loaded into the LSA, SSP DLLs have access to encrypted and plaintext passwords that are stored in Windows, such as any logged-on user's Domain password or smart card PINs. The SSP configuration is stored in two Registry keys: <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Security Packages</code> and <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\OSConfig\Security Packages</code>. An adversary may modify these Registry keys to add new SSPs, which will be loaded the next time the system boots, or when the AddSecurityPackage Windows API function is called.
(Citation: Graeber 2014)
T1103
PersistencePrivilege Escalation
Dynamic-link libraries (DLLs) that are specified in the AppInit_DLLs value in the Registry keys <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Windows</code> or <code>HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Windows</code> are loaded by user32.dll into every process that loads user32.dll. In practice this is nearly every program, since user32.dll is a very common library. (Citation: Elastic Process Injection July 2017) Similar to [Process Injection](https://attack.mitre.org/techniques/T1055), these values can be abused to obtain persistence and privilege escalation by causing a malicious DLL to be loaded and run in the context of separate processes on the computer. (Citation: AppInit Registry)
The AppInit DLL functionality is disabled in Windows 8 and later versions when secure boot is enabled. (Citation: AppInit Secure Boot)
T1109
PersistenceStealth
Some adversaries may employ sophisticated means to compromise computer components and install malicious firmware that will execute adversary code outside of the operating system and main system firmware or BIOS. This technique may be similar to [System Firmware](https://attack.mitre.org/techniques/T1019) but conducted upon other system components that may not have the same capability or level of integrity checking. Malicious device firmware could provide both a persistent level of access to systems despite potential typical failures to maintain access and hard disk re-images, as well as a way to evade host software-based defenses and integrity checks.
T1112
PersistenceDefense Impairment
Adversaries may interact with the Windows Registry as part of a variety of other techniques to aid in defense evasion, persistence, and execution.
Access to specific areas of the Registry depends on account permissions, with some keys requiring administrator-level access. The built-in Windows command-line utility [Reg](https://attack.mitre.org/software/S0075) may be used for local or remote Registry modification.(Citation: Microsoft Reg) Other tools, such as remote access tools, may also contain functionality to interact with the Registry through the Windows API.
The Registry may be modified in order to hide configuration information or malicious payloads via [Obfuscated Files or Information](https://attack.mitre.org/techniques/T1027).(Citation: Unit42 BabyShark Feb 2019)(Citation: Avaddon Ransomware 2021)(Citation: Microsoft BlackCat Jun 2022)(Citation: CISA Russian Gov Critical Infra 2018) The Registry may also be modified to impair defenses, such as by enabling macros for all Microsoft Office products, allowing privilege escalation without alerting the user, increasing the maximum number of allowed outbound requests, and/or modifying systems to store plaintext credentials in memory.(Citation: CISA LockBit 2023)(Citation: Unit42 BabyShark Feb 2019)
The Registry of a remote system may be modified to aid in execution of files as part of lateral movement. It requires the remote Registry service to be running on the target system.(Citation: Microsoft Remote) Often [Valid Accounts](https://attack.mitre.org/techniques/T1078) are required, along with access to the remote system's [SMB/Windows Admin Shares](https://attack.mitre.org/techniques/T1021/002) for RPC communication.
Finally, Registry modifications may also include actions to hide keys, such as prepending key names with a null character, which will cause an error and/or be ignored when read via [Reg](https://attack.mitre.org/software/S0075) or other utilities using the Win32 API.(Citation: Microsoft Reghide NOV 2006) Adversaries may abuse these pseudo-hidden keys to conceal payloads/commands used to maintain persistence.(Citation: TrendMicro POWELIKS AUG 2014)(Citation: SpectorOps Hiding Reg Jul 2017)
T1122
PersistenceStealth
The Component Object Model (COM) is a system within Windows to enable interaction between software components through the operating system. (Citation: Microsoft Component Object Model) Adversaries can use this system to insert malicious code that can be executed in place of legitimate software through hijacking the COM references and relationships as a means for persistence. Hijacking a COM object requires a change in the Windows Registry to replace a reference to a legitimate system component which may cause that component to not work when executed. When that system component is executed through normal system operation the adversary's code will be executed instead. (Citation: GDATA COM Hijacking) An adversary is likely to hijack objects that are used frequently enough to maintain a consistent level of persistence, but are unlikely to break noticeable functionality within the system as to avoid system instability that could lead to detection.
T1128
Persistence
Netsh.exe (also referred to as Netshell) is a command-line scripting utility used to interact with the network configuration of a system. It contains functionality to add helper DLLs for extending functionality of the utility. (Citation: TechNet Netsh) The paths to registered netsh.exe helper DLLs are entered into the Windows Registry at <code>HKLM\SOFTWARE\Microsoft\Netsh</code>.
Adversaries can use netsh.exe with helper DLLs to proxy execution of arbitrary code in a persistent manner when netsh.exe is executed automatically with another Persistence technique or if other persistent software is present on the system that executes netsh.exe as part of its normal functionality. Examples include some VPN software that invoke netsh.exe. (Citation: Demaske Netsh Persistence)
Proof of concept code exists to load Cobalt Strike's payload using netsh.exe helper DLLs. (Citation: Github Netsh Helper CS Beacon)
T1131
Persistence
Windows Authentication Package DLLs are loaded by the Local Security Authority (LSA) process at system start. They provide support for multiple logon processes and multiple security protocols to the operating system. (Citation: MSDN Authentication Packages)
Adversaries can use the autostart mechanism provided by LSA Authentication Packages for persistence by placing a reference to a binary in the Windows Registry location <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\</code> with the key value of <code>"Authentication Packages"=<target binary></code>. The binary will then be executed by the system when the authentication packages are loaded.
T1133
Initial AccessPersistence
Adversaries may leverage external-facing remote services to initially access and/or persist within a network. Remote services such as VPNs, Citrix, and other access mechanisms allow users to connect to internal enterprise network resources from external locations. There are often remote service gateways that manage connections and credential authentication for these services. Services such as [Windows Remote Management](https://attack.mitre.org/techniques/T1021/006) and [VNC](https://attack.mitre.org/techniques/T1021/005) can also be used externally.(Citation: MacOS VNC software for Remote Desktop)
Access to [Valid Accounts](https://attack.mitre.org/techniques/T1078) to use the service is often a requirement, which could be obtained through credential pharming or by obtaining the credentials from users after compromising the enterprise network.(Citation: Volexity Virtual Private Keylogging) Access to remote services may be used as a redundant or persistent access mechanism during an operation.
Access may also be gained through an exposed service that doesn’t require authentication. In containerized environments, this may include an exposed Docker API, Kubernetes API server, kubelet, or web application such as the Kubernetes dashboard.(Citation: Trend Micro Exposed Docker Server)(Citation: Unit 42 Hildegard Malware)
Adversaries may also establish persistence on network by configuring a Tor hidden service on a compromised system. Adversaries may utilize the tool `ShadowLink` to facilitate the installation and configuration of the Tor hidden service. Tor hidden service is then accessible via the Tor network because `ShadowLink` sets up a .onion address on the compromised system. `ShadowLink` may be used to forward any inbound connections to RDP, allowing the adversaries to have remote access.(Citation: The BadPilot campaign) Adversaries may get `ShadowLink` to persist on a system by masquerading it as an MS Defender application.(Citation: Russian threat actors dig in, prepare to seize on war fatigue)
T1136
Persistence
Adversaries may create an account to maintain access to victim systems.(Citation: Symantec WastedLocker June 2020) With a sufficient level of access, creating such accounts may be used to establish secondary credentialed access that does not require persistent remote access tools to be deployed on the system.
Accounts may be created on the local system or within a domain or cloud tenant. In cloud environments, adversaries may create accounts that only have access to specific services, which can reduce the chance of detection.
T1136.001
Persistence
Adversaries may create a local account to maintain access to victim systems. Local accounts are those configured by an organization for use by users, remote support, services, or for administration on a single system or service.
For example, with a sufficient level of access, the Windows <code>net user /add</code> command can be used to create a local account. In Linux, the `useradd` command can be used, while on macOS systems, the <code>dscl -create</code> command can be used. Local accounts may also be added to network devices, often via common [Network Device CLI](https://attack.mitre.org/techniques/T1059/008) commands such as <code>username</code>, to ESXi servers via `esxcli system account add`, or to Kubernetes clusters using the `kubectl` utility.(Citation: cisco_username_cmd)(Citation: Kubernetes Service Accounts Security)
Adversaries may also create new local accounts on network firewall management consoles – for example, by exploiting a vulnerable firewall management system, threat actors may be able to establish super-admin accounts that could be used to modify firewall rules and gain further access to the network.(Citation: Cyber Security News)
Such accounts may be used to establish secondary credentialed access that does not require persistent remote access tools to be deployed on the system.
T1136.002
Persistence
Adversaries may create a domain account to maintain access to victim systems. Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover user, administrator, and service accounts. With a sufficient level of access, the <code>net user /add /domain</code> command can be used to create a domain account.(Citation: Savill 1999)
Such accounts may be used to establish secondary credentialed access that does not require persistent remote access tools to be deployed on the system.
T1136.003
Persistence
Adversaries may create a cloud account to maintain access to victim systems. With a sufficient level of access, such accounts may be used to establish secondary credentialed access that does not require persistent remote access tools to be deployed on the system.(Citation: Microsoft O365 Admin Roles)(Citation: Microsoft Support O365 Add Another Admin, October 2019)(Citation: AWS Create IAM User)(Citation: GCP Create Cloud Identity Users)(Citation: Microsoft Azure AD Users)
In addition to user accounts, cloud accounts may be associated with services. Cloud providers handle the concept of service accounts in different ways. In Azure, service accounts include service principals and managed identities, which can be linked to various resources such as OAuth applications, serverless functions, and virtual machines in order to grant those resources permissions to perform various activities in the environment.(Citation: Microsoft Entra ID Service Principals) In GCP, service accounts can also be linked to specific resources, as well as be impersonated by other accounts for [Temporary Elevated Cloud Access](https://attack.mitre.org/techniques/T1548/005).(Citation: GCP Service Accounts) While AWS has no specific concept of service accounts, resources can be directly granted permission to assume roles.(Citation: AWS Instance Profiles)(Citation: AWS Lambda Execution Role)
Adversaries may create accounts that only have access to specific cloud services, which can reduce the chance of detection.
Once an adversary has created a cloud account, they can then manipulate that account to ensure persistence and allow access to additional resources - for example, by adding [Additional Cloud Credentials](https://attack.mitre.org/techniques/T1098/001) or assigning [Additional Cloud Roles](https://attack.mitre.org/techniques/T1098/003).
T1137
Persistence
Adversaries may leverage Microsoft Office-based applications for persistence between startups. Microsoft Office is a fairly common application suite on Windows-based operating systems within an enterprise network. There are multiple mechanisms that can be used with Office for persistence when an Office-based application is started; this can include the use of Office Template Macros and add-ins.
A variety of features have been discovered in Outlook that can be abused to obtain persistence, such as Outlook rules, forms, and Home Page.(Citation: SensePost Ruler GitHub) These persistence mechanisms can work within Outlook or be used through Office 365.(Citation: TechNet O365 Outlook Rules)
T1137.001
Persistence
Adversaries may abuse Microsoft Office templates to obtain persistence on a compromised system. Microsoft Office contains templates that are part of common Office applications and are used to customize styles. The base templates within the application are used each time an application starts.(Citation: Microsoft Change Normal Template)
Office Visual Basic for Applications (VBA) macros(Citation: MSDN VBA in Office) can be inserted into the base template and used to execute code when the respective Office application starts in order to obtain persistence. Examples for both Word and Excel have been discovered and published. By default, Word has a Normal.dotm template created that can be modified to include a malicious macro. Excel does not have a template file created by default, but one can be added that will automatically be loaded.(Citation: enigma0x3 normal.dotm)(Citation: Hexacorn Office Template Macros) Shared templates may also be stored and pulled from remote locations.(Citation: GlobalDotName Jun 2019)
Word Normal.dotm location:<br>
<code>C:\Users\<username>\AppData\Roaming\Microsoft\Templates\Normal.dotm</code>
Excel Personal.xlsb location:<br>
<code>C:\Users\<username>\AppData\Roaming\Microsoft\Excel\XLSTART\PERSONAL.XLSB</code>
Adversaries may also change the location of the base template to point to their own by hijacking the application's search order, e.g. Word 2016 will first look for Normal.dotm under <code>C:\Program Files (x86)\Microsoft Office\root\Office16\</code>, or by modifying the GlobalDotName registry key. By modifying the GlobalDotName registry key an adversary can specify an arbitrary location, file name, and file extension to use for the template that will be loaded on application startup. To abuse GlobalDotName, adversaries may first need to register the template as a trusted document or place it in a trusted location.(Citation: GlobalDotName Jun 2019)
An adversary may need to enable macros to execute unrestricted depending on the system or enterprise security policy on use of macros.
T1137.002
Persistence
Adversaries may abuse the Microsoft Office "Office Test" Registry key to obtain persistence on a compromised system. An Office Test Registry location exists that allows a user to specify an arbitrary DLL that will be executed every time an Office application is started. This Registry key is thought to be used by Microsoft to load DLLs for testing and debugging purposes while developing Office applications. This Registry key is not created by default during an Office installation.(Citation: Hexacorn Office Test)(Citation: Palo Alto Office Test Sofacy)
There exist user and global Registry keys for the Office Test feature, such as:
* <code>HKEY_CURRENT_USER\Software\Microsoft\Office test\Special\Perf</code>
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Office test\Special\Perf</code>
Adversaries may add this Registry key and specify a malicious DLL that will be executed whenever an Office application, such as Word or Excel, is started.
T1137.003
Persistence
Adversaries may abuse Microsoft Outlook forms to obtain persistence on a compromised system. Outlook forms are used as templates for presentation and functionality in Outlook messages. Custom Outlook forms can be created that will execute code when a specifically crafted email is sent by an adversary utilizing the same custom Outlook form.(Citation: SensePost Outlook Forms)
Once malicious forms have been added to the user’s mailbox, they will be loaded when Outlook is started. Malicious forms will execute when an adversary sends a specifically crafted email to the user.(Citation: SensePost Outlook Forms)
T1137.004
Persistence
Adversaries may abuse Microsoft Outlook's Home Page feature to obtain persistence on a compromised system. Outlook Home Page is a legacy feature used to customize the presentation of Outlook folders. This feature allows for an internal or external URL to be loaded and presented whenever a folder is opened. A malicious HTML page can be crafted that will execute code when loaded by Outlook Home Page.(Citation: SensePost Outlook Home Page)
Once malicious home pages have been added to the user’s mailbox, they will be loaded when Outlook is started. Malicious Home Pages will execute when the right Outlook folder is loaded/reloaded.(Citation: SensePost Outlook Home Page)
T1137.005
Persistence
Adversaries may abuse Microsoft Outlook rules to obtain persistence on a compromised system. Outlook rules allow a user to define automated behavior to manage email messages. A benign rule might, for example, automatically move an email to a particular folder in Outlook if it contains specific words from a specific sender. Malicious Outlook rules can be created that can trigger code execution when an adversary sends a specifically crafted email to that user.(Citation: SilentBreak Outlook Rules)
Once malicious rules have been added to the user’s mailbox, they will be loaded when Outlook is started. Malicious rules will execute when an adversary sends a specifically crafted email to the user.(Citation: SilentBreak Outlook Rules)
T1137.006
Persistence
Adversaries may abuse Microsoft Office add-ins to obtain persistence on a compromised system. Office add-ins can be used to add functionality to Office programs.(Citation: Microsoft Office Add-ins) There are different types of add-ins that can be used by the various Office products; including Word/Excel add-in Libraries (WLL/XLL), VBA add-ins, Office Component Object Model (COM) add-ins, automation add-ins, VBA Editor (VBE), Visual Studio Tools for Office (VSTO) add-ins, and Outlook add-ins.(Citation: MRWLabs Office Persistence Add-ins)(Citation: FireEye Mail CDS 2018)
Add-ins can be used to obtain persistence because they can be set to execute code when an Office application starts.
T1138
PersistencePrivilege Escalation
The Microsoft Windows Application Compatibility Infrastructure/Framework (Application Shim) was created to allow for backward compatibility of software as the operating system codebase changes over time. For example, the application shimming feature allows developers to apply fixes to applications (without rewriting code) that were created for Windows XP so that it will work with Windows 10. (Citation: Elastic Process Injection July 2017) Within the framework, shims are created to act as a buffer between the program (or more specifically, the Import Address Table) and the Windows OS. When a program is executed, the shim cache is referenced to determine if the program requires the use of the shim database (.sdb). If so, the shim database uses [Hooking](https://attack.mitre.org/techniques/T1179) to redirect the code as necessary in order to communicate with the OS.
A list of all shims currently installed by the default Windows installer (sdbinst.exe) is kept in:
* <code>%WINDIR%\AppPatch\sysmain.sdb</code>
* <code>hklm\software\microsoft\windows nt\currentversion\appcompatflags\installedsdb</code>
Custom databases are stored in:
* <code>%WINDIR%\AppPatch\custom & %WINDIR%\AppPatch\AppPatch64\Custom</code>
* <code>hklm\software\microsoft\windows nt\currentversion\appcompatflags\custom</code>
To keep shims secure, Windows designed them to run in user mode so they cannot modify the kernel and you must have administrator privileges to install a shim. However, certain shims can be used to [Bypass User Account Control](https://attack.mitre.org/techniques/T1088) (UAC) (RedirectEXE), inject DLLs into processes (InjectDLL), disable Data Execution Prevention (DisableNX) and Structure Exception Handling (DisableSEH), and intercept memory addresses (GetProcAddress). Similar to [Hooking](https://attack.mitre.org/techniques/T1179), utilizing these shims may allow an adversary to perform several malicious acts such as elevate privileges, install backdoors, disable defenses like Windows Defender, etc.
T1150
PersistencePrivilege EscalationStealth
Property list (plist) files contain all of the information that macOS and OS X uses to configure applications and services. These files are UTF-8 encoded and formatted like XML documents via a series of keys surrounded by < >. They detail when programs should execute, file paths to the executables, program arguments, required OS permissions, and many others. plists are located in certain locations depending on their purpose such as <code>/Library/Preferences</code> (which execute with elevated privileges) and <code>~/Library/Preferences</code> (which execute with a user's privileges).
Adversaries can modify these plist files to point to their own code, can use them to execute their code in the context of another user, bypass whitelisting procedures, or even use them as a persistence mechanism. (Citation: Sofacy Komplex Trojan)
T1152
ExecutionPersistenceStealth
Launchctl controls the macOS launchd process which handles things like launch agents and launch daemons, but can execute other commands or programs itself. Launchctl supports taking subcommands on the command-line, interactively, or even redirected from standard input. By loading or reloading launch agents or launch daemons, adversaries can install persistence or execute changes they made (Citation: Sofacy Komplex Trojan). Running a command from launchctl is as simple as <code>launchctl submit -l <labelName> -- /Path/to/thing/to/execute "arg" "arg" "arg"</code>. Loading, unloading, or reloading launch agents or launch daemons can require elevated privileges.
Adversaries can abuse this functionality to execute code or even bypass whitelisting if launchctl is an allowed process.
T1154
ExecutionPersistence
The <code>trap</code> command allows programs and shells to specify commands that will be executed upon receiving interrupt signals. A common situation is a script allowing for graceful termination and handling of common keyboard interrupts like <code>ctrl+c</code> and <code>ctrl+d</code>. Adversaries can use this to register code to be executed when the shell encounters specific interrupts either to gain execution or as a persistence mechanism. Trap commands are of the following format <code>trap 'command list' signals</code> where "command list" will be executed when "signals" are received.(Citation: Trap Manual)(Citation: Cyberciti Trap Statements)
T1156
Persistence
Adversaries may establish persistence through executing malicious commands triggered by a user’s shell. User shells execute several configuration scripts at different points throughout the session based on events. For example, when a user opens a command line interface or remotely logs in (such as SSH) a login shell is initiated. The login shell executes scripts from the system (/etc) and the user’s home directory (~/) to configure the environment. All login shells on a system use <code>/etc/profile</code> when initiated. These configuration scripts run at the permission level of their directory and are often used to set environment variables, create aliases, and customize the user’s environment. When the shell exits or terminates, additional shell scripts are executed to ensure the shell exits appropriately.
Adversaries may attempt to establish persistence by inserting commands into scripts automatically executed by shells. Using bash as an example, the default shell for most GNU/Linux systems, adversaries may add commands that launch malicious binaries into the <code>/etc/profile</code> and <code>/etc/profile.d</code> files (Citation: intezer-kaiji-malware). These files require root permissions and are executed each time any shell on a system launches. For user level permissions, adversaries can insert malicious commands into <code>~/.bash_profile</code>, <code>~/.bash_login</code>, or <code>~/.profile</code> (Rocke) which are sourced when a user opens a command line interface or connects remotely. Adversaries often use ~/.bash_profile since the system only executes the first file that exists in the listed order. Adversaries have also leveraged the <code>~/.bashrc</code> file (Tsunami, Rocke, Linux Rabbit, Magento) which is additionally executed if the connection is established remotely or an additional interactive shell is opened, such as a new tab in the command line interface. Some malware targets the termination of a program to trigger execution (Cannon), adversaries can use the <code>~/.bash_logout</code> file to execute malicious commands at the end of a session(Pearl_shellbot).
For macOS, the functionality of this technique is similar but leverages zsh, the default shell for macOS 10.15+. When the Terminal.app is opened, the application launches a zsh login shell and a zsh interactive shell. The login shell configures the system environment using <code>/etc/profile</code>, <code>/etc/zshenv</code>, <code>/etc/zprofile</code>, and <code>/etc/zlogin</code>. The login shell then configures the user environment with <code>~/.zprofile</code> and <code>~/.zlogin</code>. The interactive shell uses the <code>~/.zshrc<code> to configure the user environment. Upon exiting, <code>/etc/zlogout</code> and <code>~/.zlogout</code> are executed. For legacy programs, macOS executes <code>/etc/bashrc</code> on startup.
T1157
PersistencePrivilege Escalation
macOS and OS X use a common method to look for required dynamic libraries (dylib) to load into a program based on search paths. Adversaries can take advantage of ambiguous paths to plant dylibs to gain privilege escalation or persistence.
A common method is to see what dylibs an application uses, then plant a malicious version with the same name higher up in the search path. This typically results in the dylib being in the same folder as the application itself. (Citation: Writing Bad Malware for OSX) (Citation: Malware Persistence on OS X)
If the program is configured to run at a higher privilege level than the current user, then when the dylib is loaded into the application, the dylib will also run at that elevated level. This can be used by adversaries as a privilege escalation technique.
T1158
PersistenceStealth
To prevent normal users from accidentally changing special files on a system, most operating systems have the concept of a ‘hidden’ file. These files don’t show up when a user browses the file system with a GUI or when using normal commands on the command line. Users must explicitly ask to show the hidden files either via a series of Graphical User Interface (GUI) prompts or with command line switches (<code>dir /a</code> for Windows and <code>ls –a</code> for Linux and macOS).
Adversaries can use this to their advantage to hide files and folders anywhere on the system for persistence and evading a typical user or system analysis that does not incorporate investigation of hidden files.
### Windows
Users can mark specific files as hidden by using the attrib.exe binary. Simply do <code>attrib +h filename</code> to mark a file or folder as hidden. Similarly, the “+s” marks a file as a system file and the “+r” flag marks the file as read only. Like most windows binaries, the attrib.exe binary provides the ability to apply these changes recursively “/S”.
### Linux/Mac
Users can mark specific files as hidden simply by putting a “.” as the first character in the file or folder name (Citation: Sofacy Komplex Trojan) (Citation: Antiquated Mac Malware). Files and folder that start with a period, ‘.’, are by default hidden from being viewed in the Finder application and standard command-line utilities like “ls”. Users must specifically change settings to have these files viewable. For command line usages, there is typically a flag to see all files (including hidden ones). To view these files in the Finder Application, the following command must be executed: <code>defaults write com.apple.finder AppleShowAllFiles YES</code>, and then relaunch the Finder Application.
### Mac
Files on macOS can be marked with the UF_HIDDEN flag which prevents them from being seen in Finder.app, but still allows them to be seen in Terminal.app (Citation: WireLurker).
Many applications create these hidden files and folders to store information so that it doesn’t clutter up the user’s workspace. For example, SSH utilities create a .ssh folder that’s hidden and contains the user’s known hosts and keys.
T1159
Persistence
Per Apple’s developer documentation, when a user logs in, a per-user launchd process is started which loads the parameters for each launch-on-demand user agent from the property list (plist) files found in <code>/System/Library/LaunchAgents</code>, <code>/Library/LaunchAgents</code>, and <code>$HOME/Library/LaunchAgents</code> (Citation: AppleDocs Launch Agent Daemons) (Citation: OSX Keydnap malware) (Citation: Antiquated Mac Malware). These launch agents have property list files which point to the executables that will be launched (Citation: OSX.Dok Malware).
Adversaries may install a new launch agent that can be configured to execute at login by using launchd or launchctl to load a plist into the appropriate directories (Citation: Sofacy Komplex Trojan) (Citation: Methods of Mac Malware Persistence). The agent name may be disguised by using a name from a related operating system or benign software. Launch Agents are created with user level privileges and are executed with the privileges of the user when they log in (Citation: OSX Malware Detection) (Citation: OceanLotus for OS X). They can be set up to execute when a specific user logs in (in the specific user’s directory structure) or when any user logs in (which requires administrator privileges).
T1160
PersistencePrivilege Escalation
Per Apple’s developer documentation, when macOS and OS X boot up, launchd is run to finish system initialization. This process loads the parameters for each launch-on-demand system-level daemon from the property list (plist) files found in <code>/System/Library/LaunchDaemons</code> and <code>/Library/LaunchDaemons</code> (Citation: AppleDocs Launch Agent Daemons). These LaunchDaemons have property list files which point to the executables that will be launched (Citation: Methods of Mac Malware Persistence).
Adversaries may install a new launch daemon that can be configured to execute at startup by using launchd or launchctl to load a plist into the appropriate directories (Citation: OSX Malware Detection). The daemon name may be disguised by using a name from a related operating system or benign software (Citation: WireLurker). Launch Daemons may be created with administrator privileges, but are executed under root privileges, so an adversary may also use a service to escalate privileges from administrator to root.
The plist file permissions must be root:wheel, but the script or program that it points to has no such requirement. So, it is possible for poor configurations to allow an adversary to modify a current Launch Daemon’s executable and gain persistence or Privilege Escalation.
T1161
Persistence
Mach-O binaries have a series of headers that are used to perform certain operations when a binary is loaded. The LC_LOAD_DYLIB header in a Mach-O binary tells macOS and OS X which dynamic libraries (dylibs) to load during execution time. These can be added ad-hoc to the compiled binary as long adjustments are made to the rest of the fields and dependencies (Citation: Writing Bad Malware for OSX). There are tools available to perform these changes. Any changes will invalidate digital signatures on binaries because the binary is being modified. Adversaries can remediate this issue by simply removing the LC_CODE_SIGNATURE command from the binary so that the signature isn’t checked at load time (Citation: Malware Persistence on OS X).
T1162
Persistence
MacOS provides the option to list specific applications to run when a user logs in. These applications run under the logged in user's context, and will be started every time the user logs in. Login items installed using the Service Management Framework are not visible in the System Preferences and can only be removed by the application that created them (Citation: Adding Login Items). Users have direct control over login items installed using a shared file list which are also visible in System Preferences (Citation: Adding Login Items). These login items are stored in the user's <code>~/Library/Preferences/</code> directory in a plist file called <code>com.apple.loginitems.plist</code> (Citation: Methods of Mac Malware Persistence). Some of these applications can open visible dialogs to the user, but they don’t all have to since there is an option to ‘Hide’ the window. If an adversary can register their own login item or modified an existing one, then they can use it to execute their code for a persistence mechanism each time the user logs in (Citation: Malware Persistence on OS X) (Citation: OSX.Dok Malware). The API method <code> SMLoginItemSetEnabled </code> can be used to set Login Items, but scripting languages like [AppleScript](https://attack.mitre.org/techniques/T1155) can do this as well (Citation: Adding Login Items).
T1163
Persistence
During the boot process, macOS executes <code>source /etc/rc.common</code>, which is a shell script containing various utility functions. This file also defines routines for processing command-line arguments and for gathering system settings, and is thus recommended to include in the start of Startup Item Scripts (Citation: Startup Items). In macOS and OS X, this is now a deprecated technique in favor of launch agents and launch daemons, but is currently still used.
Adversaries can use the rc.common file as a way to hide code for persistence that will execute on each reboot as the root user (Citation: Methods of Mac Malware Persistence).
T1164
Persistence
Starting in Mac OS X 10.7 (Lion), users can specify certain applications to be re-opened when a user reboots their machine. While this is usually done via a Graphical User Interface (GUI) on an app-by-app basis, there are property list files (plist) that contain this information as well located at <code>~/Library/Preferences/com.apple.loginwindow.plist</code> and <code>~/Library/Preferences/ByHost/com.apple.loginwindow.* .plist</code>.
An adversary can modify one of these files directly to include a link to their malicious executable to provide a persistence mechanism each time the user reboots their machine (Citation: Methods of Mac Malware Persistence).
T1165
PersistencePrivilege Escalation
Per Apple’s documentation, startup items execute during the final phase of the boot process and contain shell scripts or other executable files along with configuration information used by the system to determine the execution order for all startup items (Citation: Startup Items). This is technically a deprecated version (superseded by Launch Daemons), and thus the appropriate folder, <code>/Library/StartupItems</code> isn’t guaranteed to exist on the system by default, but does appear to exist by default on macOS Sierra. A startup item is a directory whose executable and configuration property list (plist), <code>StartupParameters.plist</code>, reside in the top-level directory.
An adversary can create the appropriate folders/files in the StartupItems directory to register their own persistence mechanism (Citation: Methods of Mac Malware Persistence). Additionally, since StartupItems run during the bootup phase of macOS, they will run as root. If an adversary is able to modify an existing Startup Item, then they will be able to Privilege Escalate as well.
T1166
PersistencePrivilege Escalation
When the setuid or setgid bits are set on Linux or macOS for an application, this means that the application will run with the privileges of the owning user or group respectively (Citation: setuid man page). Normally an application is run in the current user’s context, regardless of which user or group owns the application. There are instances where programs need to be executed in an elevated context to function properly, but the user running them doesn’t need the elevated privileges. Instead of creating an entry in the sudoers file, which must be done by root, any user can specify the setuid or setgid flag to be set for their own applications. These bits are indicated with an "s" instead of an "x" when viewing a file's attributes via <code>ls -l</code>. The <code>chmod</code> program can set these bits with via bitmasking, <code>chmod 4777 [file]</code> or via shorthand naming, <code>chmod u+s [file]</code>.
An adversary can take advantage of this to either do a shell escape or exploit a vulnerability in an application with the setsuid or setgid bits to get code running in a different user’s context. Additionally, adversaries can use this mechanism on their own malware to make sure they're able to execute in elevated contexts in the future (Citation: OSX Keydnap malware).
T1168
ExecutionPersistence
On Linux and macOS systems, multiple methods are supported for creating pre-scheduled and periodic background jobs: cron, (Citation: Die.net Linux crontab Man Page) at, (Citation: Die.net Linux at Man Page) and launchd. (Citation: AppleDocs Scheduling Timed Jobs) Unlike [Scheduled Task/Job](https://attack.mitre.org/techniques/T1053) on Windows systems, job scheduling on Linux-based systems cannot be done remotely unless used in conjunction within an established remote session, like secure shell (SSH).
### cron
System-wide cron jobs are installed by modifying <code>/etc/crontab</code> file, <code>/etc/cron.d/</code> directory or other locations supported by the Cron daemon, while per-user cron jobs are installed using crontab with specifically formatted crontab files. (Citation: AppleDocs Scheduling Timed Jobs) This works on macOS and Linux systems.
Those methods allow for commands or scripts to be executed at specific, periodic intervals in the background without user interaction. An adversary may use job scheduling to execute programs at system startup or on a scheduled basis for Persistence, (Citation: Janicab) (Citation: Methods of Mac Malware Persistence) (Citation: Malware Persistence on OS X) (Citation: Avast Linux Trojan Cron Persistence) to conduct Execution as part of Lateral Movement, to gain root privileges, or to run a process under the context of a specific account.
### at
The at program is another means on POSIX-based systems, including macOS and Linux, to schedule a program or script job for execution at a later date and/or time, which could also be used for the same purposes.
### launchd
Each launchd job is described by a different configuration property list (plist) file similar to [Launch Daemon](https://attack.mitre.org/techniques/T1160) or [Launch Agent](https://attack.mitre.org/techniques/T1159), except there is an additional key called <code>StartCalendarInterval</code> with a dictionary of time values. (Citation: AppleDocs Scheduling Timed Jobs) This only works on macOS and OS X.
T1176
Persistence
Adversaries may abuse software extensions to establish persistent access to victim systems. Software extensions are modular components that enhance or customize the functionality of software applications, including web browsers, Integrated Development Environments (IDEs), and other platforms.(Citation: Chrome Extension C2 Malware)(Citation: Abramovsky VSCode Security) Extensions are typically installed via official marketplaces, app stores, or manually loaded by users, and they often inherit the permissions and access levels of the host application.
Malicious extensions can be introduced through various methods, including social engineering, compromised marketplaces, or direct installation by users or by adversaries who have already gained access to a system. Malicious extensions can be named similarly or identically to benign extensions in marketplaces. Security mechanisms in extension marketplaces may be insufficient to detect malicious components, allowing adversaries to bypass automated scanners or exploit trust established during the installation process. Adversaries may also abuse benign extensions to achieve their objectives, such as using legitimate functionality to tunnel data or bypass security controls.
The modular nature of extensions and their integration with host applications make them an attractive target for adversaries seeking to exploit trusted software ecosystems. Detection can be challenging due to the inherent trust placed in extensions during installation and their ability to blend into normal application workflows.
T1176.001
Persistence
Adversaries may abuse internet browser extensions to establish persistent access to victim systems. Browser extensions or plugins are small programs that can add functionality to and customize aspects of internet browsers. They can be installed directly via a local file or custom URL or through a browser's app store - an official online platform where users can browse, install, and manage extensions for a specific web browser. Extensions generally inherit the web browser's permissions previously granted.(Citation: Wikipedia Browser Extension)(Citation: Chrome Extensions Definition)
Malicious extensions can be installed into a browser through malicious app store downloads masquerading as legitimate extensions, through social engineering, or by an adversary that has already compromised a system. Security can be limited on browser app stores, so it may not be difficult for malicious extensions to defeat automated scanners.(Citation: Malicious Chrome Extension Numbers) Depending on the browser, adversaries may also manipulate an extension's update url to install updates from an adversary-controlled server or manipulate the mobile configuration file to silently install additional extensions.
Adversaries may abuse how chromium-based browsers load extensions by modifying or replacing the Preferences and/or Secure Preferences files to silently install malicious extensions. When the browser is not running, adversaries can alter these files, ensuring the extension is loaded, granted desired permissions, and will persist in browser sessions. This method does not require user consent and extensions are silently loaded in the background from disk or from the browser's trusted store.(Citation: Pulsedive)
Previous to macOS 11, adversaries could silently install browser extensions via the command line using the <code>profiles</code> tool to install malicious <code>.mobileconfig</code> files. In macOS 11+, the use of the <code>profiles</code> tool can no longer install configuration profiles; however, <code>.mobileconfig</code> files can be planted and installed with user interaction.(Citation: xorrior chrome extensions macOS)
Once the extension is installed, it can browse to websites in the background, steal all information that a user enters into a browser (including credentials), and be used as an installer for a RAT for persistence.(Citation: Chrome Extension Crypto Miner)(Citation: ICEBRG Chrome Extensions)(Citation: Banker Google Chrome Extension Steals Creds)(Citation: Catch All Chrome Extension)
There have also been instances of botnets using a persistent backdoor through malicious Chrome extensions for [Command and Control](https://attack.mitre.org/tactics/TA0011).(Citation: Stantinko Botnet)(Citation: Chrome Extension C2 Malware) Adversaries may also use browser extensions to modify browser permissions and components, privacy settings, and other security controls for [Stealth](https://attack.mitre.org/tactics/TA0005).(Citation: Browers FriarFox)(Citation: Browser Adrozek)
T1176.002
Persistence
Adversaries may abuse an integrated development environment (IDE) extension to establish persistent access to victim systems.(Citation: Mnemonic misuse visual studio) IDEs such as Visual Studio Code, IntelliJ IDEA, and Eclipse support extensions - software components that add features like code linting, auto-completion, task automation, or integration with tools like Git and Docker. A malicious extension can be installed through an extension marketplace (i.e., [Compromise Software Dependencies and Development Tools](https://attack.mitre.org/techniques/T1195/001)) or side-loaded directly into the IDE.(Citation: Abramovsky VSCode Security)(Citation: Lakshmanan Visual Studio Marketplace)
In addition to installing malicious extensions, adversaries may also leverage benign ones. For example, adversaries may establish persistent SSH tunnels via the use of the VSCode Remote SSH extension (i.e., [IDE Tunneling](https://attack.mitre.org/techniques/T1219/001)).
Trust is typically established through the installation process; once installed, the malicious extension is run every time that the IDE is launched. The extension can then be used to execute arbitrary code, establish a backdoor, mine cryptocurrency, or exfiltrate data.(Citation: ExtensionTotal VSCode Extensions 2025)
T1177
ExecutionPersistence
The Windows security subsystem is a set of components that manage and enforce the security policy for a computer or domain. The Local Security Authority (LSA) is the main component responsible for local security policy and user authentication. The LSA includes multiple dynamic link libraries (DLLs) associated with various other security functions, all of which run in the context of the LSA Subsystem Service (LSASS) lsass.exe process. (Citation: Microsoft Security Subsystem)
Adversaries may target lsass.exe drivers to obtain execution and/or persistence. By either replacing or adding illegitimate drivers (e.g., [DLL Side-Loading](https://attack.mitre.org/techniques/T1073) or [DLL Search Order Hijacking](https://attack.mitre.org/techniques/T1038)), an adversary can achieve arbitrary code execution triggered by continuous LSA operations.
T1179
PersistencePrivilege EscalationCredential Access
Windows processes often leverage application programming interface (API) functions to perform tasks that require reusable system resources. Windows API functions are typically stored in dynamic-link libraries (DLLs) as exported functions.
Hooking involves redirecting calls to these functions and can be implemented via:
* **Hooks procedures**, which intercept and execute designated code in response to events such as messages, keystrokes, and mouse inputs. (Citation: Microsoft Hook Overview) (Citation: Elastic Process Injection July 2017)
* **Import address table (IAT) hooking**, which use modifications to a process’s IAT, where pointers to imported API functions are stored. (Citation: Elastic Process Injection July 2017) (Citation: Adlice Software IAT Hooks Oct 2014) (Citation: MWRInfoSecurity Dynamic Hooking 2015)
* **Inline hooking**, which overwrites the first bytes in an API function to redirect code flow. (Citation: Elastic Process Injection July 2017) (Citation: HighTech Bridge Inline Hooking Sept 2011) (Citation: MWRInfoSecurity Dynamic Hooking 2015)
Similar to [Process Injection](https://attack.mitre.org/techniques/T1055), adversaries may use hooking to load and execute malicious code within the context of another process, masking the execution while also allowing access to the process's memory and possibly elevated privileges. Installing hooking mechanisms may also provide Persistence via continuous invocation when the functions are called through normal use.
Malicious hooking mechanisms may also capture API calls that include parameters that reveal user authentication credentials for Credential Access. (Citation: Microsoft TrojanSpy:Win32/Ursnif.gen!I Sept 2017)
Hooking is commonly utilized by [Rootkit](https://attack.mitre.org/techniques/T1014)s to conceal files, processes, Registry keys, and other objects in order to hide malware and associated behaviors. (Citation: Symantec Windows Rootkits)
T1180
Persistence
Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension.(Citation: Wikipedia Screensaver) The Windows screensaver application scrnsave.scr is located in <code>C:\Windows\System32\</code>, and <code>C:\Windows\sysWOW64\</code> on 64-bit Windows systems, along with screensavers included with base Windows installations.
The following screensaver settings are stored in the Registry (<code>HKCU\Control Panel\Desktop\</code>) and could be manipulated to achieve persistence:
* <code>SCRNSAVE.exe</code> - set to malicious PE path
* <code>ScreenSaveActive</code> - set to '1' to enable the screensaver
* <code>ScreenSaverIsSecure</code> - set to '0' to not require a password to unlock
* <code>ScreenSaveTimeout</code> - sets user inactivity timeout before screensaver is executed
Adversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity. (Citation: ESET Gazer Aug 2017)
T1182
PersistencePrivilege Escalation
Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs Registry key under <code>HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager</code> are loaded into every process that calls the ubiquitously used application programming interface (API) functions CreateProcess, CreateProcessAsUser, CreateProcessWithLoginW, CreateProcessWithTokenW, or WinExec. (Citation: Elastic Process Injection July 2017)
Similar to [Process Injection](https://attack.mitre.org/techniques/T1055), this value can be abused to obtain persistence and privilege escalation by causing a malicious DLL to be loaded and run in the context of separate processes on the computer.
T1183
PersistencePrivilege EscalationStealth
Image File Execution Options (IFEO) enable a developer to attach a debugger to an application. When a process is created, a debugger present in an application’s IFEO will be prepended to the application’s name, effectively launching the new process under the debugger (e.g., “C:\dbg\ntsd.exe -g notepad.exe”). (Citation: Microsoft Dev Blog IFEO Mar 2010)
IFEOs can be set directly via the Registry or in Global Flags via the GFlags tool. (Citation: Microsoft GFlags Mar 2017) IFEOs are represented as <code>Debugger</code> values in the Registry under <code>HKLM\SOFTWARE{\Wow6432Node}\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\<executable></code> where <code><executable></code> is the binary on which the debugger is attached. (Citation: Microsoft Dev Blog IFEO Mar 2010)
IFEOs can also enable an arbitrary monitor program to be launched when a specified program silently exits (i.e. is prematurely terminated by itself or a second, non kernel-mode process). (Citation: Microsoft Silent Process Exit NOV 2017) (Citation: Oddvar Moe IFEO APR 2018) Similar to debuggers, silent exit monitoring can be enabled through GFlags and/or by directly modifying IEFO and silent process exit Registry values in <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\</code>. (Citation: Microsoft Silent Process Exit NOV 2017) (Citation: Oddvar Moe IFEO APR 2018)
An example where the evil.exe process is started when notepad.exe exits: (Citation: Oddvar Moe IFEO APR 2018)
* <code>reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\notepad.exe" /v GlobalFlag /t REG_DWORD /d 512</code>
* <code>reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\notepad.exe" /v ReportingMode /t REG_DWORD /d 1</code>
* <code>reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\notepad.exe" /v MonitorProcess /d "C:\temp\evil.exe"</code>
Similar to [Process Injection](https://attack.mitre.org/techniques/T1055), these values may be abused to obtain persistence and privilege escalation by causing a malicious executable to be loaded and run in the context of separate processes on the computer. (Citation: Elastic Process Injection July 2017) Installing IFEO mechanisms may also provide Persistence via continuous invocation.
Malware may also use IFEO for Defense Evasion by registering invalid debuggers that redirect and effectively disable various system and security applications. (Citation: FSecure Hupigon) (Citation: Symantec Ushedix June 2008)
T1197
ExecutionPersistenceStealth
Adversaries may abuse BITS jobs to persistently execute code and perform various background tasks. Windows Background Intelligent Transfer Service (BITS) is a low-bandwidth, asynchronous file transfer mechanism exposed through [Component Object Model](https://attack.mitre.org/techniques/T1559/001) (COM).(Citation: Microsoft COM)(Citation: Microsoft BITS) BITS is commonly used by updaters, messengers, and other applications preferred to operate in the background (using available idle bandwidth) without interrupting other networked applications. File transfer tasks are implemented as BITS jobs, which contain a queue of one or more file operations.
The interface to create and manage BITS jobs is accessible through [PowerShell](https://attack.mitre.org/techniques/T1059/001) and the [BITSAdmin](https://attack.mitre.org/software/S0190) tool.(Citation: Microsoft BITS)(Citation: Microsoft BITSAdmin)
Adversaries may abuse BITS to download (e.g. [Ingress Tool Transfer](https://attack.mitre.org/techniques/T1105)), execute, and even clean up after running malicious code (e.g. [Indicator Removal](https://attack.mitre.org/techniques/T1070)). BITS tasks are self-contained in the BITS job database, without new files or registry modifications, and often permitted by host firewalls.(Citation: CTU BITS Malware June 2016)(Citation: Mondok Windows PiggyBack BITS May 2007)(Citation: Symantec BITS May 2007) BITS enabled execution may also enable persistence by creating long-standing jobs (the default maximum lifetime is 90 days and extendable) or invoking an arbitrary program when a job completes or errors (including after system reboots).(Citation: PaloAlto UBoatRAT Nov 2017)(Citation: CTU BITS Malware June 2016)
BITS upload functionalities can also be used to perform [Exfiltration Over Alternative Protocol](https://attack.mitre.org/techniques/T1048).(Citation: CTU BITS Malware June 2016)
T1198
PersistenceStealth
In user mode, Windows Authenticode (Citation: Microsoft Authenticode) digital signatures are used to verify a file's origin and integrity, variables that may be used to establish trust in signed code (ex: a driver with a valid Microsoft signature may be handled as safe). The signature validation process is handled via the WinVerifyTrust application programming interface (API) function, (Citation: Microsoft WinVerifyTrust) which accepts an inquiry and coordinates with the appropriate trust provider, which is responsible for validating parameters of a signature. (Citation: SpectorOps Subverting Trust Sept 2017)
Because of the varying executable file types and corresponding signature formats, Microsoft created software components called Subject Interface Packages (SIPs) (Citation: EduardosBlog SIPs July 2008) to provide a layer of abstraction between API functions and files. SIPs are responsible for enabling API functions to create, retrieve, calculate, and verify signatures. Unique SIPs exist for most file formats (Executable, PowerShell, Installer, etc., with catalog signing providing a catch-all (Citation: Microsoft Catalog Files and Signatures April 2017)) and are identified by globally unique identifiers (GUIDs). (Citation: SpectorOps Subverting Trust Sept 2017)
Similar to [Code Signing](https://attack.mitre.org/techniques/T1116), adversaries may abuse this architecture to subvert trust controls and bypass security policies that allow only legitimately signed code to execute on a system. Adversaries may hijack SIP and trust provider components to mislead operating system and whitelisting tools to classify malicious (or any) code as signed by: (Citation: SpectorOps Subverting Trust Sept 2017)
* Modifying the <code>Dll</code> and <code>FuncName</code> Registry values in <code>HKLM\SOFTWARE[\WOW6432Node\]Microsoft\Cryptography\OID\EncodingType 0\CryptSIPDllGetSignedDataMsg\{SIP_GUID}</code> that point to the dynamic link library (DLL) providing a SIP’s CryptSIPDllGetSignedDataMsg function, which retrieves an encoded digital certificate from a signed file. By pointing to a maliciously-crafted DLL with an exported function that always returns a known good signature value (ex: a Microsoft signature for Portable Executables) rather than the file’s real signature, an adversary can apply an acceptable signature value to all files using that SIP (Citation: GitHub SIP POC Sept 2017) (although a hash mismatch will likely occur, invalidating the signature, since the hash returned by the function will not match the value computed from the file).
* Modifying the <code>Dll</code> and <code>FuncName</code> Registry values in <code>HKLM\SOFTWARE\[WOW6432Node\]Microsoft\Cryptography\OID\EncodingType 0\CryptSIPDllVerifyIndirectData\{SIP_GUID}</code> that point to the DLL providing a SIP’s CryptSIPDllVerifyIndirectData function, which validates a file’s computed hash against the signed hash value. By pointing to a maliciously-crafted DLL with an exported function that always returns TRUE (indicating that the validation was successful), an adversary can successfully validate any file (with a legitimate signature) using that SIP (Citation: GitHub SIP POC Sept 2017) (with or without hijacking the previously mentioned CryptSIPDllGetSignedDataMsg function). This Registry value could also be redirected to a suitable exported function from an already present DLL, avoiding the requirement to drop and execute a new file on disk.
* Modifying the <code>DLL</code> and <code>Function</code> Registry values in <code>HKLM\SOFTWARE\[WOW6432Node\]Microsoft\Cryptography\Providers\Trust\FinalPolicy\{trust provider GUID}</code> that point to the DLL providing a trust provider’s FinalPolicy function, which is where the decoded and parsed signature is checked and the majority of trust decisions are made. Similar to hijacking SIP’s CryptSIPDllVerifyIndirectData function, this value can be redirected to a suitable exported function from an already present DLL or a maliciously-crafted DLL (though the implementation of a trust provider is complex).
* **Note:** The above hijacks are also possible without modifying the Registry via [DLL Search Order Hijacking](https://attack.mitre.org/techniques/T1038).
Hijacking SIP or trust provider components can also enable persistent code execution, since these malicious components may be invoked by any application that performs code signing or signature validation. (Citation: SpectorOps Subverting Trust Sept 2017)
T1205
PersistenceStealthCommand and Control
Adversaries may use traffic signaling to hide open ports or other malicious functionality used for persistence or command and control. Traffic signaling involves the use of a magic value or sequence that must be sent to a system to trigger a special response, such as opening a closed port or executing a malicious task. This may take the form of sending a series of packets with certain characteristics before a port will be opened that the adversary can use for command and control. Usually this series of packets consists of attempted connections to a predefined sequence of closed ports (i.e. [Port Knocking](https://attack.mitre.org/techniques/T1205/001)), but can involve unusual flags, specific strings, or other unique characteristics. After the sequence is completed, opening a port may be accomplished by the host-based firewall, but could also be implemented by custom software.
Adversaries may also communicate with an already open port, but the service listening on that port will only respond to commands or trigger other malicious functionality if passed the appropriate magic value(s).
The observation of the signal packets to trigger the communication can be conducted through different methods. One means, originally implemented by Cd00r,(Citation: Hartrell cd00r 2002) is to use the libpcap libraries to sniff for the packets in question. Another method leverages raw sockets, which enables the malware to use ports that are already open for use by other programs.
On network devices, adversaries may use crafted packets to enable [Network Device Authentication](https://attack.mitre.org/techniques/T1556/004) for standard services offered by the device such as telnet. Such signaling may also be used to open a closed service port such as telnet, or to trigger module modification of malware implants on the device, adding, removing, or changing malicious capabilities. Adversaries may use crafted packets to attempt to connect to one or more (open or closed) ports, but may also attempt to connect to a router interface, broadcast, and network address IP on the same port in order to achieve their goals and objectives.(Citation: Cisco Synful Knock Evolution)(Citation: Mandiant - Synful Knock)(Citation: Cisco Blog Legacy Device Attacks) To enable this traffic signaling on embedded devices, adversaries must first achieve and leverage [Patch System Image](https://attack.mitre.org/techniques/T1601/001) due to the monolithic nature of the architecture.
Adversaries may also use the Wake-on-LAN feature to turn on powered off systems. Wake-on-LAN is a hardware feature that allows a powered down system to be powered on, or woken up, by sending a magic packet to it. Once the system is powered on, it may become a target for lateral movement.(Citation: Bleeping Computer - Ryuk WoL)(Citation: AMD Magic Packet)
T1205.001
PersistenceStealthCommand and Control
Adversaries may use port knocking to hide open ports used for persistence or command and control. To enable a port, an adversary sends a series of attempted connections to a predefined sequence of closed ports. After the sequence is completed, opening a port is often accomplished by the host based firewall, but could also be implemented by custom software.
This technique has been observed both for the dynamic opening of a listening port as well as the initiating of a connection to a listening server on a different system.
The observation of the signal packets to trigger the communication can be conducted through different methods. One means, originally implemented by Cd00r,(Citation: Hartrell cd00r 2002) is to use the libpcap libraries to sniff for the packets in question. Another method leverages raw sockets, which enables the malware to use ports that are already open for use by other programs.
T1205.002
PersistenceStealthCommand and Control
Adversaries may attach filters to a network socket to monitor then activate backdoors used for persistence or command and control. With elevated permissions, adversaries can use features such as the `libpcap` library to open sockets and install filters to allow or disallow certain types of data to come through the socket. The filter may apply to all traffic passing through the specified network interface (or every interface if not specified). When the network interface receives a packet matching the filter criteria, additional actions can be triggered on the host, such as activation of a reverse shell.
To establish a connection, an adversary sends a crafted packet to the targeted host that matches the installed filter criteria.(Citation: haking9 libpcap network sniffing) Adversaries have used these socket filters to trigger the installation of implants, conduct ping backs, and to invoke command shells. Communication with these socket filters may also be used in conjunction with [Protocol Tunneling](https://attack.mitre.org/techniques/T1572).(Citation: exatrack bpf filters passive backdoors)(Citation: Leonardo Turla Penquin May 2020)
Filters can be installed on any Unix-like platform with `libpcap` installed or on Windows hosts using `Winpcap`. Adversaries may use either `libpcap` with `pcap_setfilter` or the standard library function `setsockopt` with `SO_ATTACH_FILTER` options. Since the socket connection is not active until the packet is received, this behavior may be difficult to detect due to the lack of activity on a host, low CPU overhead, and limited visibility into raw socket usage.
T1209
Persistence
The Windows Time service (W32Time) enables time synchronization across and within domains. (Citation: Microsoft W32Time Feb 2018) W32Time time providers are responsible for retrieving time stamps from hardware/network resources and outputting these values to other network clients. (Citation: Microsoft TimeProvider)
Time providers are implemented as dynamic-link libraries (DLLs) that are registered in the subkeys of <code>HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\W32Time\TimeProviders\</code>. (Citation: Microsoft TimeProvider) The time provider manager, directed by the service control manager, loads and starts time providers listed and enabled under this key at system startup and/or whenever parameters are changed. (Citation: Microsoft TimeProvider)
Adversaries may abuse this architecture to establish Persistence, specifically by registering and enabling a malicious DLL as a time provider. Administrator privileges are required for time provider registration, though execution will run in context of the Local Service account. (Citation: Github W32Time Oct 2017)
T1215
Persistence
Loadable Kernel Modules (or LKMs) are pieces of code that can be loaded and unloaded into the kernel upon demand. They extend the functionality of the kernel without the need to reboot the system. For example, one type of module is the device driver, which allows the kernel to access hardware connected to the system. (Citation: Linux Kernel Programming) When used maliciously, Loadable Kernel Modules (LKMs) can be a type of kernel-mode [Rootkit](https://attack.mitre.org/techniques/T1014) that run with the highest operating system privilege (Ring 0). (Citation: Linux Kernel Module Programming Guide) Adversaries can use loadable kernel modules to covertly persist on a system and evade defenses. Examples have been found in the wild and there are some open source projects. (Citation: Volatility Phalanx2) (Citation: CrowdStrike Linux Rootkit) (Citation: GitHub Reptile) (Citation: GitHub Diamorphine)
Common features of LKM based rootkits include: hiding itself, selective hiding of files, processes and network activity, as well as log tampering, providing authenticated backdoors and enabling root access to non-privileged users. (Citation: iDefense Rootkit Overview)
Kernel extensions, also called kext, are used for macOS to load functionality onto a system similar to LKMs for Linux. They are loaded and unloaded through <code>kextload</code> and <code>kextunload</code> commands. Several examples have been found where this can be used. (Citation: RSAC 2015 San Francisco Patrick Wardle) (Citation: Synack Secure Kernel Extension Broken) Examples have been found in the wild. (Citation: Securelist Ventir)
T1501
Persistence
Systemd services can be used to establish persistence on a Linux system. The systemd service manager is commonly used for managing background daemon processes (also known as services) and other system resources.(Citation: Linux man-pages: systemd January 2014)(Citation: Freedesktop.org Linux systemd 29SEP2018) Systemd is the default initialization (init) system on many Linux distributions starting with Debian 8, Ubuntu 15.04, CentOS 7, RHEL 7, Fedora 15, and replaces legacy init systems including SysVinit and Upstart while remaining backwards compatible with the aforementioned init systems.
Systemd utilizes configuration files known as service units to control how services boot and under what conditions. By default, these unit files are stored in the <code>/etc/systemd/system</code> and <code>/usr/lib/systemd/system</code> directories and have the file extension <code>.service</code>. Each service unit file may contain numerous directives that can execute system commands.
* ExecStart, ExecStartPre, and ExecStartPost directives cover execution of commands when a services is started manually by 'systemctl' or on system start if the service is set to automatically start.
* ExecReload directive covers when a service restarts.
* ExecStop and ExecStopPost directives cover when a service is stopped or manually by 'systemctl'.
Adversaries have used systemd functionality to establish persistent access to victim systems by creating and/or modifying service unit files that cause systemd to execute malicious commands at recurring intervals, such as at system boot.(Citation: Anomali Rocke March 2019)(Citation: gist Arch package compromise 10JUL2018)(Citation: Arch Linux Package Systemd Compromise BleepingComputer 10JUL2018)(Citation: acroread package compromised Arch Linux Mail 8JUL2018)
While adversaries typically require root privileges to create/modify service unit files in the <code>/etc/systemd/system</code> and <code>/usr/lib/systemd/system</code> directories, low privilege users can create/modify service unit files in directories such as <code>~/.config/systemd/user/</code> to achieve user-level persistence.(Citation: Rapid7 Service Persistence 22JUNE2016)
T1504
PersistencePrivilege Escalation
Adversaries may gain persistence and elevate privileges in certain situations by abusing [PowerShell](https://attack.mitre.org/techniques/T1086) profiles. A PowerShell profile (<code>profile.ps1</code>) is a script that runs when PowerShell starts and can be used as a logon script to customize user environments. PowerShell supports several profiles depending on the user or host program. For example, there can be different profiles for PowerShell host programs such as the PowerShell console, PowerShell ISE or Visual Studio Code. An administrator can also configure a profile that applies to all users and host programs on the local computer. (Citation: Microsoft About Profiles)
Adversaries may modify these profiles to include arbitrary commands, functions, modules, and/or PowerShell drives to gain persistence. Every time a user opens a PowerShell session the modified script will be executed unless the <code>-NoProfile</code> flag is used when it is launched. (Citation: ESET Turla PowerShell May 2019)
An adversary may also be able to escalate privileges if a script in a PowerShell profile is loaded and executed by an account with higher privileges, such as a domain administrator. (Citation: Wits End and Shady PowerShell Profiles)
T1505
Persistence
Adversaries may abuse legitimate extensible development features of servers to establish persistent access to systems. Enterprise server applications may include features that allow developers to write and install software or scripts to extend the functionality of the main application. Adversaries may install malicious components to extend and abuse server applications.(Citation: volexity_0day_sophos_FW)
T1505.001
Persistence
Adversaries may abuse SQL stored procedures to establish persistent access to systems. SQL Stored Procedures are code that can be saved and reused so that database users do not waste time rewriting frequently used SQL queries. Stored procedures can be invoked via SQL statements to the database using the procedure name or via defined events (e.g. when a SQL server application is started/restarted).
Adversaries may craft malicious stored procedures that can provide a persistence mechanism in SQL database servers.(Citation: NetSPI Startup Stored Procedures)(Citation: Kaspersky MSSQL Aug 2019) To execute operating system commands through SQL syntax the adversary may have to enable additional functionality, such as xp_cmdshell for MSSQL Server.(Citation: NetSPI Startup Stored Procedures)(Citation: Kaspersky MSSQL Aug 2019)(Citation: Microsoft xp_cmdshell 2017)
Microsoft SQL Server can enable common language runtime (CLR) integration. With CLR integration enabled, application developers can write stored procedures using any .NET framework language (e.g. VB .NET, C#, etc.).(Citation: Microsoft CLR Integration 2017) Adversaries may craft or modify CLR assemblies that are linked to stored procedures since these CLR assemblies can be made to execute arbitrary commands.(Citation: NetSPI SQL Server CLR)
T1505.002
Persistence
Adversaries may abuse Microsoft transport agents to establish persistent access to systems. Microsoft Exchange transport agents can operate on email messages passing through the transport pipeline to perform various tasks such as filtering spam, filtering malicious attachments, journaling, or adding a corporate signature to the end of all outgoing emails.(Citation: Microsoft TransportAgent Jun 2016)(Citation: ESET LightNeuron May 2019) Transport agents can be written by application developers and then compiled to .NET assemblies that are subsequently registered with the Exchange server. Transport agents will be invoked during a specified stage of email processing and carry out developer defined tasks.
Adversaries may register a malicious transport agent to provide a persistence mechanism in Exchange Server that can be triggered by adversary-specified email events.(Citation: ESET LightNeuron May 2019) Though a malicious transport agent may be invoked for all emails passing through the Exchange transport pipeline, the agent can be configured to only carry out specific tasks in response to adversary defined criteria. For example, the transport agent may only carry out an action like copying in-transit attachments and saving them for later exfiltration if the recipient email address matches an entry on a list provided by the adversary.
T1505.003
Persistence
Adversaries may backdoor web servers with web shells to establish persistent access to systems. A Web shell is a Web script that is placed on an openly accessible Web server to allow an adversary to access the Web server as a gateway into a network. A Web shell may provide a set of functions to execute or a command-line interface on the system that hosts the Web server.(Citation: volexity_0day_sophos_FW)
In addition to a server-side script, a Web shell may have a client interface program that is used to talk to the Web server (e.g. [China Chopper](https://attack.mitre.org/software/S0020) Web shell client).(Citation: Lee 2013)
T1505.004
Persistence
Adversaries may install malicious components that run on Internet Information Services (IIS) web servers to establish persistence. IIS provides several mechanisms to extend the functionality of the web servers. For example, Internet Server Application Programming Interface (ISAPI) extensions and filters can be installed to examine and/or modify incoming and outgoing IIS web requests. Extensions and filters are deployed as DLL files that export three functions: <code>Get{Extension/Filter}Version</code>, <code>Http{Extension/Filter}Proc</code>, and (optionally) <code>Terminate{Extension/Filter}</code>. IIS modules may also be installed to extend IIS web servers.(Citation: Microsoft ISAPI Extension Overview 2017)(Citation: Microsoft ISAPI Filter Overview 2017)(Citation: IIS Backdoor 2011)(Citation: Trustwave IIS Module 2013)
Adversaries may install malicious ISAPI extensions and filters to observe and/or modify traffic, execute commands on compromised machines, or proxy command and control traffic. ISAPI extensions and filters may have access to all IIS web requests and responses. For example, an adversary may abuse these mechanisms to modify HTTP responses in order to distribute malicious commands/content to previously comprised hosts.(Citation: Microsoft ISAPI Filter Overview 2017)(Citation: Microsoft ISAPI Extension Overview 2017)(Citation: Microsoft ISAPI Extension All Incoming 2017)(Citation: Dell TG-3390)(Citation: Trustwave IIS Module 2013)(Citation: MMPC ISAPI Filter 2012)
Adversaries may also install malicious IIS modules to observe and/or modify traffic. IIS 7.0 introduced modules that provide the same unrestricted access to HTTP requests and responses as ISAPI extensions and filters. IIS modules can be written as a DLL that exports <code>RegisterModule</code>, or as a .NET application that interfaces with ASP.NET APIs to access IIS HTTP requests.(Citation: Microsoft IIS Modules Overview 2007)(Citation: Trustwave IIS Module 2013)(Citation: ESET IIS Malware 2021)
T1505.005
Persistence
Adversaries may abuse components of Terminal Services to enable persistent access to systems. Microsoft Terminal Services, renamed to Remote Desktop Services in some Windows Server OSs as of 2022, enable remote terminal connections to hosts. Terminal Services allows servers to transmit a full, interactive, graphical user interface to clients via RDP.(Citation: Microsoft Remote Desktop Services)
[Windows Service](https://attack.mitre.org/techniques/T1543/003)s that are run as a "generic" process (ex: <code>svchost.exe</code>) load the service's DLL file, the location of which is stored in a Registry entry named <code>ServiceDll</code>.(Citation: Microsoft System Services Fundamentals) The <code>termsrv.dll</code> file, typically stored in `%SystemRoot%\System32\`, is the default <code>ServiceDll</code> value for Terminal Services in `HKLM\System\CurrentControlSet\services\TermService\Parameters\`.
Adversaries may modify and/or replace the Terminal Services DLL to enable persistent access to victimized hosts.(Citation: James TermServ DLL) Modifications to this DLL could be done to execute arbitrary payloads (while also potentially preserving normal <code>termsrv.dll</code> functionality) as well as to simply enable abusable features of Terminal Services. For example, an adversary may enable features such as concurrent [Remote Desktop Protocol](https://attack.mitre.org/techniques/T1021/001) sessions by either patching the <code>termsrv.dll</code> file or modifying the <code>ServiceDll</code> value to point to a DLL that provides increased RDP functionality.(Citation: Windows OS Hub RDP)(Citation: RDPWrap Github) On a non-server Windows OS this increased functionality may also enable an adversary to avoid Terminal Services prompts that warn/log out users of a system when a new RDP session is created.
T1505.006
Persistence
Adversaries may abuse vSphere Installation Bundles (VIBs) to establish persistent access to ESXi hypervisors. VIBs are collections of files used for software distribution and virtual system management in VMware environments. Since ESXi uses an in-memory filesystem where changes made to most files are stored in RAM rather than in persistent storage, these modifications are lost after a reboot. However, VIBs can be used to create startup tasks, apply custom firewall rules, or deploy binaries that persist across reboots. Typically, administrators use VIBs for updates and system maintenance.
VIBs can be broken down into three components:(Citation: VMware VIBs)
* VIB payload: a `.vgz` archive containing the directories and files to be created and executed on boot when the VIBs are loaded.
* Signature file: verifies the host acceptance level of a VIB, indicating what testing and validation has been done by VMware or its partners before publication of a VIB. By default, ESXi hosts require a minimum acceptance level of PartnerSupported for VIB installation, meaning the VIB is published by a trusted VMware partner. However, privileged users can change the default acceptance level using the `esxcli` command line interface. Additionally, VIBs are able to be installed regardless of acceptance level by using the <code> esxcli software vib install --force</code> command.
* XML descriptor file: a configuration file containing associated VIB metadata, such as the name of the VIB and its dependencies.
Adversaries may leverage malicious VIB packages to maintain persistent access to ESXi hypervisors, allowing system changes to be executed upon each bootup of ESXi – such as using `esxcli` to enable firewall rules for backdoor traffic, creating listeners on hard coded ports, and executing backdoors.(Citation: Google Cloud Threat Intelligence ESXi VIBs 2022) Adversaries may also masquerade their malicious VIB files as PartnerSupported by modifying the XML descriptor file.(Citation: Google Cloud Threat Intelligence ESXi VIBs 2022)
T1519
PersistencePrivilege Escalation
Adversaries may use Event Monitor Daemon (emond) to establish persistence by scheduling malicious commands to run on predictable event triggers. Emond is a [Launch Daemon](https://attack.mitre.org/techniques/T1160) that accepts events from various services, runs them through a simple rules engine, and takes action. The emond binary at <code>/sbin/emond</code> will load any rules from the <code>/etc/emond.d/rules/</code> directory and take action once an explicitly defined event takes place. The rule files are in the plist format and define the name, event type, and action to take. Some examples of event types include system startup and user authentication. Examples of actions are to run a system command or send an email. The emond service will not launch if there is no file present in the QueueDirectories path <code>/private/var/db/emondClients</code>, specified in the [Launch Daemon](https://attack.mitre.org/techniques/T1160) configuration file at<code>/System/Library/LaunchDaemons/com.apple.emond.plist</code>.(Citation: xorrior emond Jan 2018)(Citation: magnusviri emond Apr 2016)(Citation: sentinelone macos persist Jun 2019)
Adversaries may abuse this service by writing a rule to execute commands when a defined event occurs, such as system start up or user authentication.(Citation: xorrior emond Jan 2018)(Citation: magnusviri emond Apr 2016)(Citation: sentinelone macos persist Jun 2019) Adversaries may also be able to escalate privileges from administrator to root as the emond service is executed with root privileges by the [Launch Daemon](https://attack.mitre.org/techniques/T1160) service.
T1525
Persistence
Adversaries may implant cloud or container images with malicious code to establish persistence after gaining access to an environment. Amazon Web Services (AWS) Amazon Machine Images (AMIs), Google Cloud Platform (GCP) Images, and Azure Images as well as popular container runtimes such as Docker can be implanted or backdoored. Unlike [Upload Malware](https://attack.mitre.org/techniques/T1608/001), this technique focuses on adversaries implanting an image in a registry within a victim’s environment. Depending on how the infrastructure is provisioned, this could provide persistent access if the infrastructure provisioning tool is instructed to always use the latest image.(Citation: Rhino Labs Cloud Image Backdoor Technique Sept 2019)
A tool has been developed to facilitate planting backdoors in cloud container images.(Citation: Rhino Labs Cloud Backdoor September 2019) If an adversary has access to a compromised AWS instance, and permissions to list the available container images, they may implant a backdoor such as a [Web Shell](https://attack.mitre.org/techniques/T1505/003).(Citation: Rhino Labs Cloud Image Backdoor Technique Sept 2019)
T1542
PersistenceStealth
Adversaries may abuse Pre-OS Boot mechanisms as a way to establish persistence on a system. During the booting process of a computer, firmware and various startup services are loaded before the operating system. These programs control flow of execution before the operating system takes control.(Citation: Wikipedia Booting)
Adversaries may overwrite data in boot drivers or firmware such as BIOS (Basic Input/Output System) and The Unified Extensible Firmware Interface (UEFI) to persist on systems at a layer below the operating system. This can be particularly difficult to detect as malware at this level will not be detected by host software-based defenses.
T1542.001
PersistenceStealth
Adversaries may modify system firmware to persist on systems.The BIOS (Basic Input/Output System) and The Unified Extensible Firmware Interface (UEFI) or Extensible Firmware Interface (EFI) are examples of system firmware that operate as the software interface between the operating system and hardware of a computer.(Citation: Wikipedia BIOS)(Citation: Wikipedia UEFI)(Citation: About UEFI)
System firmware like BIOS and (U)EFI underly the functionality of a computer and may be modified by an adversary to perform or assist in malicious activity. Capabilities exist to overwrite the system firmware, which may give sophisticated adversaries a means to install malicious firmware updates as a means of persistence on a system that may be difficult to detect.
T1542.002
PersistenceStealth
Adversaries may modify component firmware to persist on systems. Some adversaries may employ sophisticated means to compromise computer components and install malicious firmware that will execute adversary code outside of the operating system and main system firmware or BIOS. This technique may be similar to [System Firmware](https://attack.mitre.org/techniques/T1542/001) but conducted upon other system components/devices that may not have the same capability or level of integrity checking.
Malicious component firmware could provide both a persistent level of access to systems despite potential typical failures to maintain access and hard disk re-images, as well as a way to evade host software-based defenses and integrity checks.
T1542.003
PersistenceStealth
Adversaries may use bootkits to persist on systems. A bootkit is a malware variant that modifies the boot sectors of a hard drive, allowing malicious code to execute before a computer's operating system has loaded. Bootkits reside at a layer below the operating system and may make it difficult to perform full remediation unless an organization suspects one was used and can act accordingly.
In BIOS systems, a bootkit may modify the Master Boot Record (MBR) and/or Volume Boot Record (VBR).(Citation: Mandiant M Trends 2016) The MBR is the section of disk that is first loaded after completing hardware initialization by the BIOS. It is the location of the boot loader. An adversary who has raw access to the boot drive may overwrite this area, diverting execution during startup from the normal boot loader to adversary code.(Citation: Lau 2011)
The MBR passes control of the boot process to the VBR. Similar to the case of MBR, an adversary who has raw access to the boot drive may overwrite the VBR to divert execution during startup to adversary code.
In UEFI (Unified Extensible Firmware Interface) systems, a bootkit may instead create or modify files in the EFI system partition (ESP). The ESP is a partition on data storage used by devices containing UEFI that allows the system to boot the OS and other utilities used by the system. An adversary can use the newly created or patched files in the ESP to run malicious kernel code.(Citation: Microsoft Security)(Citation: welivesecurity)
T1542.004
PersistenceStealth
Adversaries may abuse the ROM Monitor (ROMMON) by loading an unauthorized firmware with adversary code to provide persistent access and manipulate device behavior that is difficult to detect.(Citation: Cisco Synful Knock Evolution)(Citation: Cisco Blog Legacy Device Attacks)
ROMMON is a Cisco network device firmware that functions as a boot loader, boot image, or boot helper to initialize hardware and software when the platform is powered on or reset. Similar to [TFTP Boot](https://attack.mitre.org/techniques/T1542/005), an adversary may upgrade the ROMMON image locally or remotely (for example, through TFTP) with adversary code and restart the device in order to overwrite the existing ROMMON image. This provides adversaries with the means to update the ROMMON to gain persistence on a system in a way that may be difficult to detect.
T1542.005
PersistenceStealth
Adversaries may abuse netbooting to load an unauthorized network device operating system from a Trivial File Transfer Protocol (TFTP) server. TFTP boot (netbooting) is commonly used by network administrators to load configuration-controlled network device images from a centralized management server. Netbooting is one option in the boot sequence and can be used to centralize, manage, and control device images.
Adversaries may manipulate the configuration on the network device specifying use of a malicious TFTP server, which may be used in conjunction with [Modify System Image](https://attack.mitre.org/techniques/T1601) to load a modified image on device startup or reset. The unauthorized image allows adversaries to modify device configuration, add malicious capabilities to the device, and introduce backdoors to maintain control of the network device while minimizing detection through use of a standard functionality. This technique is similar to [ROMMONkit](https://attack.mitre.org/techniques/T1542/004) and may result in the network device running a modified image.(Citation: Cisco Blog Legacy Device Attacks)
T1543
PersistencePrivilege Escalation
Adversaries may create or modify system-level processes to repeatedly execute malicious payloads as part of persistence. When operating systems boot up, they can start processes that perform background system functions. On Windows and Linux, these system processes are referred to as services.(Citation: TechNet Services) On macOS, launchd processes known as [Launch Daemon](https://attack.mitre.org/techniques/T1543/004) and [Launch Agent](https://attack.mitre.org/techniques/T1543/001) are run to finish system initialization and load user specific parameters.(Citation: AppleDocs Launch Agent Daemons)
Adversaries may install new services, daemons, or agents that can be configured to execute at startup or a repeatable interval in order to establish persistence. Similarly, adversaries may modify existing services, daemons, or agents to achieve the same effect.
Services, daemons, or agents may be created with administrator privileges but executed under root/SYSTEM privileges. Adversaries may leverage this functionality to create or modify system processes in order to escalate privileges.(Citation: OSX Malware Detection)
T1543.001
PersistencePrivilege Escalation
Adversaries may create or modify launch agents to repeatedly execute malicious payloads as part of persistence. When a user logs in, a per-user launchd process is started which loads the parameters for each launch-on-demand user agent from the property list (.plist) file found in <code>/System/Library/LaunchAgents</code>, <code>/Library/LaunchAgents</code>, and <code>~/Library/LaunchAgents</code>.(Citation: AppleDocs Launch Agent Daemons)(Citation: OSX Keydnap malware)(Citation: Antiquated Mac Malware) Property list files use the <code>Label</code>, <code>ProgramArguments </code>, and <code>RunAtLoad</code> keys to identify the Launch Agent's name, executable location, and execution time.(Citation: OSX.Dok Malware) Launch Agents are often installed to perform updates to programs, launch user specified programs at login, or to conduct other developer tasks.
Launch Agents can also be executed using the [Launchctl](https://attack.mitre.org/techniques/T1569/001) command.
Adversaries may install a new Launch Agent that executes at login by placing a .plist file into the appropriate folders with the <code>RunAtLoad</code> or <code>KeepAlive</code> keys set to <code>true</code>.(Citation: Sofacy Komplex Trojan)(Citation: Methods of Mac Malware Persistence) The Launch Agent name may be disguised by using a name from the related operating system or benign software. Launch Agents are created with user level privileges and execute with user level permissions.(Citation: OSX Malware Detection)(Citation: OceanLotus for OS X)
T1543.002
PersistencePrivilege Escalation
Adversaries may create or modify systemd services to repeatedly execute malicious payloads as part of persistence. Systemd is a system and service manager commonly used for managing background daemon processes (also known as services) and other system resources.(Citation: Linux man-pages: systemd January 2014) Systemd is the default initialization (init) system on many Linux distributions replacing legacy init systems, including SysVinit and Upstart, while remaining backwards compatible.
Systemd utilizes unit configuration files with the `.service` file extension to encode information about a service's process. By default, system level unit files are stored in the `/systemd/system` directory of the root owned directories (`/`). User level unit files are stored in the `/systemd/user` directories of the user owned directories (`$HOME`).(Citation: lambert systemd 2022)
Inside the `.service` unit files, the following directives are used to execute commands:(Citation: freedesktop systemd.service)
* `ExecStart`, `ExecStartPre`, and `ExecStartPost` directives execute when a service is started manually by `systemctl` or on system start if the service is set to automatically start.
* `ExecReload` directive executes when a service restarts.
* `ExecStop`, `ExecStopPre`, and `ExecStopPost` directives execute when a service is stopped.
Adversaries have created new service files, altered the commands a `.service` file’s directive executes, and modified the user directive a `.service` file executes as, which could result in privilege escalation. Adversaries may also place symbolic links in these directories, enabling systemd to find these payloads regardless of where they reside on the filesystem.(Citation: Anomali Rocke March 2019)(Citation: airwalk backdoor unix systems)(Citation: Rapid7 Service Persistence 22JUNE2016)
The `.service` file’s User directive can be used to run service as a specific user, which could result in privilege escalation based on specific user/group permissions.
Systemd services can be created via systemd generators, which support the dynamic generation of unit files. Systemd generators are small executables that run during boot or configuration reloads to dynamically create or modify systemd unit files by converting non-native configurations into services, symlinks, or drop-ins (i.e., [Boot or Logon Initialization Scripts](https://attack.mitre.org/techniques/T1037)).(Citation: Elastic Security Labs Linux Persistence 2024)(Citation: Pepe Berba Systemd 2022)
T1543.003
PersistencePrivilege Escalation
Adversaries may create or modify Windows services to repeatedly execute malicious payloads as part of persistence. When Windows boots up, it starts programs or applications called services that perform background system functions.(Citation: TechNet Services) Windows service configuration information, including the file path to the service's executable or recovery programs/commands, is stored in the Windows Registry.
Adversaries may install a new service or modify an existing service to execute at startup in order to persist on a system. Service configurations can be set or modified using system utilities (such as sc.exe), by directly modifying the Registry, or by interacting directly with the Windows API.
Adversaries may also use services to install and execute malicious drivers. For example, after dropping a driver file (ex: `.sys`) to disk, the payload can be loaded and registered via [Native API](https://attack.mitre.org/techniques/T1106) functions such as `CreateServiceW()` (or manually via functions such as `ZwLoadDriver()` and `ZwSetValueKey()`), by creating the required service Registry values (i.e. [Modify Registry](https://attack.mitre.org/techniques/T1112)), or by using command-line utilities such as `PnPUtil.exe`.(Citation: Symantec W.32 Stuxnet Dossier)(Citation: Crowdstrike DriveSlayer February 2022)(Citation: Unit42 AcidBox June 2020) Adversaries may leverage these drivers as [Rootkit](https://attack.mitre.org/techniques/T1014)s to hide the presence of malicious activity on a system. Adversaries may also load a signed yet vulnerable driver onto a compromised machine (known as "Bring Your Own Vulnerable Driver" (BYOVD)) as part of [Exploitation for Privilege Escalation](https://attack.mitre.org/techniques/T1068).(Citation: ESET InvisiMole June 2020)(Citation: Unit42 AcidBox June 2020)
Services may be created with administrator privileges but are executed under SYSTEM privileges, so an adversary may also use a service to escalate privileges. Adversaries may also directly start services through [Service Execution](https://attack.mitre.org/techniques/T1569/002).
To make detection analysis more challenging, malicious services may also incorporate [Masquerade Task or Service](https://attack.mitre.org/techniques/T1036/004) (ex: using a service and/or payload name related to a legitimate OS or benign software component). Adversaries may also create ‘hidden’ services (i.e., [Hide Artifacts](https://attack.mitre.org/techniques/T1564)), for example by using the `sc sdset` command to set service permissions via the Service Descriptor Definition Language (SDDL). This may hide a Windows service from the view of standard service enumeration methods such as `Get-Service`, `sc query`, and `services.exe`.(Citation: SANS 1)(Citation: SANS 2)
T1543.004
PersistencePrivilege Escalation
Adversaries may create or modify Launch Daemons to execute malicious payloads as part of persistence. Launch Daemons are plist files used to interact with Launchd, the service management framework used by macOS. Launch Daemons require elevated privileges to install, are executed for every user on a system prior to login, and run in the background without the need for user interaction. During the macOS initialization startup, the launchd process loads the parameters for launch-on-demand system-level daemons from plist files found in <code>/System/Library/LaunchDaemons/</code> and <code>/Library/LaunchDaemons/</code>. Required Launch Daemons parameters include a <code>Label</code> to identify the task, <code>Program</code> to provide a path to the executable, and <code>RunAtLoad</code> to specify when the task is run. Launch Daemons are often used to provide access to shared resources, updates to software, or conduct automation tasks.(Citation: AppleDocs Launch Agent Daemons)(Citation: Methods of Mac Malware Persistence)(Citation: launchd Keywords for plists)
Adversaries may install a Launch Daemon configured to execute at startup by using the <code>RunAtLoad</code> parameter set to <code>true</code> and the <code>Program</code> parameter set to the malicious executable path. The daemon name may be disguised by using a name from a related operating system or benign software (i.e. [Masquerading](https://attack.mitre.org/techniques/T1036)). When the Launch Daemon is executed, the program inherits administrative permissions.(Citation: WireLurker)(Citation: OSX Malware Detection)
Additionally, system configuration changes (such as the installation of third party package managing software) may cause folders such as <code>usr/local/bin</code> to become globally writeable. So, it is possible for poor configurations to allow an adversary to modify executables referenced by current Launch Daemon's plist files.(Citation: LaunchDaemon Hijacking)(Citation: sentinelone macos persist Jun 2019)
T1543.005
PersistencePrivilege Escalation
Adversaries may create or modify container or container cluster management tools that run as daemons, agents, or services on individual hosts. These include software for creating and managing individual containers, such as Docker and Podman, as well as container cluster node-level agents such as kubelet. By modifying these services, an adversary may be able to achieve persistence or escalate their privileges on a host.
For example, by using the `docker run` or `podman run` command with the `restart=always` directive, a container can be configured to persistently restart on the host.(Citation: AquaSec TeamTNT 2023) A user with access to the (rootful) docker command may also be able to escalate their privileges on the host.(Citation: GTFOBins Docker)
In Kubernetes environments, DaemonSets allow an adversary to persistently [Deploy Container](https://attack.mitre.org/techniques/T1610)s on all nodes, including ones added later to the cluster.(Citation: Aquasec Kubernetes Attack 2023)(Citation: Kubernetes DaemonSet) Pods can also be deployed to specific nodes using the `nodeSelector` or `nodeName` fields in the pod spec.(Citation: Kubernetes Assigning Pods to Nodes)(Citation: AppSecco Kubernetes Namespace Breakout 2020)
Note that containers can also be configured to run as [Systemd Service](https://attack.mitre.org/techniques/T1543/002)s.(Citation: Podman Systemd)(Citation: Docker Systemd)
T1546
PersistencePrivilege Escalation
Adversaries may establish persistence and/or elevate privileges using system mechanisms that trigger execution based on specific events. Various operating systems have means to monitor and subscribe to events such as logons or other user activity such as running specific applications/binaries. Cloud environments may also support various functions and services that monitor and can be invoked in response to specific cloud events.(Citation: Backdooring an AWS account)(Citation: Varonis Power Automate Data Exfiltration)(Citation: Microsoft DART Case Report 001)
Adversaries may abuse these mechanisms as a means of maintaining persistent access to a victim via repeatedly executing malicious code. After gaining access to a victim system, adversaries may create/modify event triggers to point to malicious content that will be executed whenever the event trigger is invoked.(Citation: FireEye WMI 2015)(Citation: Malware Persistence on OS X)(Citation: amnesia malware)
Since the execution can be proxied by an account with higher permissions, such as SYSTEM or service accounts, an adversary may be able to abuse these triggered execution mechanisms to escalate their privileges.
T1546.001
PersistencePrivilege Escalation
Adversaries may establish persistence by executing malicious content triggered by a file type association. When a file is opened, the default program used to open the file (also called the file association or handler) is checked. File association selections are stored in the Windows Registry and can be edited by users, administrators, or programs that have Registry access or by administrators using the built-in assoc utility.(Citation: Microsoft Change Default Programs)(Citation: Microsoft File Handlers)(Citation: Microsoft Assoc Oct 2017) Applications can modify the file association for a given file extension to call an arbitrary program when a file with the given extension is opened.
System file associations are listed under <code>HKEY_CLASSES_ROOT\.[extension]</code>, for example <code>HKEY_CLASSES_ROOT\.txt</code>. The entries point to a handler for that extension located at <code>HKEY_CLASSES_ROOT\\[handler]</code>. The various commands are then listed as subkeys underneath the shell key at <code>HKEY_CLASSES_ROOT\\[handler]\shell\\[action]\command</code>. For example:
* <code>HKEY_CLASSES_ROOT\txtfile\shell\open\command</code>
* <code>HKEY_CLASSES_ROOT\txtfile\shell\print\command</code>
* <code>HKEY_CLASSES_ROOT\txtfile\shell\printto\command</code>
The values of the keys listed are commands that are executed when the handler opens the file extension. Adversaries can modify these values to continually execute arbitrary commands.(Citation: TrendMicro TROJ-FAKEAV OCT 2012)
T1546.002
PersistencePrivilege Escalation
Adversaries may establish persistence by executing malicious content triggered by user inactivity. Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension.(Citation: Wikipedia Screensaver) The Windows screensaver application scrnsave.scr is located in <code>C:\Windows\System32\</code>, and <code>C:\Windows\sysWOW64\</code> on 64-bit Windows systems, along with screensavers included with base Windows installations.
The following screensaver settings are stored in the Registry (<code>HKCU\Control Panel\Desktop\</code>) and could be manipulated to achieve persistence:
* <code>SCRNSAVE.exe</code> - set to malicious PE path
* <code>ScreenSaveActive</code> - set to '1' to enable the screensaver
* <code>ScreenSaverIsSecure</code> - set to '0' to not require a password to unlock
* <code>ScreenSaveTimeout</code> - sets user inactivity timeout before screensaver is executed
Adversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity.(Citation: ESET Gazer Aug 2017)
T1546.003
PersistencePrivilege Escalation
Adversaries may establish persistence and elevate privileges by executing malicious content triggered by a Windows Management Instrumentation (WMI) event subscription. WMI can be used to install event filters, providers, consumers, and bindings that execute code when a defined event occurs. Examples of events that may be subscribed to are the wall clock time, user login, or the computer's uptime.(Citation: Mandiant M-Trends 2015)
Adversaries may use the capabilities of WMI to subscribe to an event and execute arbitrary code when that event occurs, providing persistence on a system.(Citation: FireEye WMI SANS 2015)(Citation: FireEye WMI 2015) Adversaries may also compile WMI scripts – using `mofcomp.exe` –into Windows Management Object (MOF) files (.mof extension) that can be used to create a malicious subscription.(Citation: Dell WMI Persistence)(Citation: Microsoft MOF May 2018)
WMI subscription execution is proxied by the WMI Provider Host process (WmiPrvSe.exe) and thus may result in elevated SYSTEM privileges.
T1546.004
PersistencePrivilege Escalation
Adversaries may establish persistence through executing malicious commands triggered by a user’s shell. User [Unix Shell](https://attack.mitre.org/techniques/T1059/004)s execute several configuration scripts at different points throughout the session based on events. For example, when a user opens a command-line interface or remotely logs in (such as via SSH) a login shell is initiated. The login shell executes scripts from the system (<code>/etc</code>) and the user’s home directory (<code>~/</code>) to configure the environment. All login shells on a system use /etc/profile when initiated. These configuration scripts run at the permission level of their directory and are often used to set environment variables, create aliases, and customize the user’s environment. When the shell exits or terminates, additional shell scripts are executed to ensure the shell exits appropriately.
Adversaries may attempt to establish persistence by inserting commands into scripts automatically executed by shells. Using bash as an example, the default shell for most GNU/Linux systems, adversaries may add commands that launch malicious binaries into the <code>/etc/profile</code> and <code>/etc/profile.d</code> files.(Citation: intezer-kaiji-malware)(Citation: bencane blog bashrc) These files typically require root permissions to modify and are executed each time any shell on a system launches. For user level permissions, adversaries can insert malicious commands into <code>~/.bash_profile</code>, <code>~/.bash_login</code>, or <code>~/.profile</code> which are sourced when a user opens a command-line interface or connects remotely.(Citation: anomali-rocke-tactics)(Citation: Linux manual bash invocation) Since the system only executes the first existing file in the listed order, adversaries have used <code>~/.bash_profile</code> to ensure execution. Adversaries have also leveraged the <code>~/.bashrc</code> file which is additionally executed if the connection is established remotely or an additional interactive shell is opened, such as a new tab in the command-line interface.(Citation: Tsunami)(Citation: anomali-rocke-tactics)(Citation: anomali-linux-rabbit)(Citation: Magento) Some malware targets the termination of a program to trigger execution, adversaries can use the <code>~/.bash_logout</code> file to execute malicious commands at the end of a session.
For macOS, the functionality of this technique is similar but may leverage zsh, the default shell for macOS 10.15+. When the Terminal.app is opened, the application launches a zsh login shell and a zsh interactive shell. The login shell configures the system environment using <code>/etc/profile</code>, <code>/etc/zshenv</code>, <code>/etc/zprofile</code>, and <code>/etc/zlogin</code>.(Citation: ScriptingOSX zsh)(Citation: PersistentJXA_leopitt)(Citation: code_persistence_zsh)(Citation: macOS MS office sandbox escape) The login shell then configures the user environment with <code>~/.zprofile</code> and <code>~/.zlogin</code>. The interactive shell uses the <code>~/.zshrc</code> to configure the user environment. Upon exiting, <code>/etc/zlogout</code> and <code>~/.zlogout</code> are executed. For legacy programs, macOS executes <code>/etc/bashrc</code> on startup.
T1546.005
PersistencePrivilege Escalation
Adversaries may establish persistence by executing malicious content triggered by an interrupt signal. The <code>trap</code> command allows programs and shells to specify commands that will be executed upon receiving interrupt signals. A common situation is a script allowing for graceful termination and handling of common keyboard interrupts like <code>ctrl+c</code> and <code>ctrl+d</code>.
Adversaries can use this to register code to be executed when the shell encounters specific interrupts as a persistence mechanism. Trap commands are of the following format <code>trap 'command list' signals</code> where "command list" will be executed when "signals" are received.(Citation: Trap Manual)(Citation: Cyberciti Trap Statements)
T1546.006
PersistencePrivilege Escalation
Adversaries may establish persistence by executing malicious content triggered by the execution of tainted binaries. Mach-O binaries have a series of headers that are used to perform certain operations when a binary is loaded. The LC_LOAD_DYLIB header in a Mach-O binary tells macOS and OS X which dynamic libraries (dylibs) to load during execution time. These can be added ad-hoc to the compiled binary as long as adjustments are made to the rest of the fields and dependencies.(Citation: Writing Bad Malware for OSX) There are tools available to perform these changes.
Adversaries may modify Mach-O binary headers to load and execute malicious dylibs every time the binary is executed. Although any changes will invalidate digital signatures on binaries because the binary is being modified, this can be remediated by simply removing the LC_CODE_SIGNATURE command from the binary so that the signature isn’t checked at load time.(Citation: Malware Persistence on OS X)
T1546.007
PersistencePrivilege Escalation
Adversaries may establish persistence by executing malicious content triggered by Netsh Helper DLLs. Netsh.exe (also referred to as Netshell) is a command-line scripting utility used to interact with the network configuration of a system. It contains functionality to add helper DLLs for extending functionality of the utility.(Citation: TechNet Netsh) The paths to registered netsh.exe helper DLLs are entered into the Windows Registry at <code>HKLM\SOFTWARE\Microsoft\Netsh</code>.
Adversaries can use netsh.exe helper DLLs to trigger execution of arbitrary code in a persistent manner. This execution would take place anytime netsh.exe is executed, which could happen automatically, with another persistence technique, or if other software (ex: VPN) is present on the system that executes netsh.exe as part of its normal functionality.(Citation: Github Netsh Helper CS Beacon)(Citation: Demaske Netsh Persistence)
T1546.008
PersistencePrivilege Escalation
Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by accessibility features. Windows contains accessibility features that may be launched with a key combination before a user has logged in (ex: when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system.
Two common accessibility programs are <code>C:\Windows\System32\sethc.exe</code>, launched when the shift key is pressed five times and <code>C:\Windows\System32\utilman.exe</code>, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as "sticky keys", and has been used by adversaries for unauthenticated access through a remote desktop login screen.(Citation: FireEye Hikit Rootkit)
Depending on the version of Windows, an adversary may take advantage of these features in different ways. Common methods used by adversaries include replacing accessibility feature binaries or pointers/references to these binaries in the Registry. In newer versions of Windows, the replaced binary needs to be digitally signed for x64 systems, the binary must reside in <code>%systemdir%\</code>, and it must be protected by Windows File or Resource Protection (WFP/WRP).(Citation: DEFCON2016 Sticky Keys) The [Image File Execution Options Injection](https://attack.mitre.org/techniques/T1546/012) debugger method was likely discovered as a potential workaround because it does not require the corresponding accessibility feature binary to be replaced.
For simple binary replacement on Windows XP and later as well as Windows Server 2003/R2 and later, for example, the program (e.g., <code>C:\Windows\System32\utilman.exe</code>) may be replaced with "cmd.exe" (or another program that provides backdoor access). Subsequently, pressing the appropriate key combination at the login screen while sitting at the keyboard or when connected over [Remote Desktop Protocol](https://attack.mitre.org/techniques/T1021/001) will cause the replaced file to be executed with SYSTEM privileges.(Citation: Tilbury 2014)
Other accessibility features exist that may also be leveraged in a similar fashion:(Citation: DEFCON2016 Sticky Keys)(Citation: Narrator Accessibility Abuse)
* On-Screen Keyboard: <code>C:\Windows\System32\osk.exe</code>
* Magnifier: <code>C:\Windows\System32\Magnify.exe</code>
* Narrator: <code>C:\Windows\System32\Narrator.exe</code>
* Display Switcher: <code>C:\Windows\System32\DisplaySwitch.exe</code>
* App Switcher: <code>C:\Windows\System32\AtBroker.exe</code>
T1546.009
PersistencePrivilege Escalation
Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by AppCert DLLs loaded into processes. Dynamic-link libraries (DLLs) that are specified in the <code>AppCertDLLs</code> Registry key under <code>HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\</code> are loaded into every process that calls the ubiquitously used application programming interface (API) functions <code>CreateProcess</code>, <code>CreateProcessAsUser</code>, <code>CreateProcessWithLoginW</code>, <code>CreateProcessWithTokenW</code>, or <code>WinExec</code>.(Citation: Elastic Process Injection July 2017)
Similar to [Process Injection](https://attack.mitre.org/techniques/T1055), this value can be abused to obtain elevated privileges by causing a malicious DLL to be loaded and run in the context of separate processes on the computer. Malicious AppCert DLLs may also provide persistence by continuously being triggered by API activity.
T1546.010
PersistencePrivilege Escalation
Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by AppInit DLLs loaded into processes. Dynamic-link libraries (DLLs) that are specified in the <code>AppInit_DLLs</code> value in the Registry keys <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Windows</code> or <code>HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Windows</code> are loaded by user32.dll into every process that loads user32.dll. In practice this is nearly every program, since user32.dll is a very common library.(Citation: Elastic Process Injection July 2017)
Similar to Process Injection, these values can be abused to obtain elevated privileges by causing a malicious DLL to be loaded and run in the context of separate processes on the computer.(Citation: AppInit Registry) Malicious AppInit DLLs may also provide persistence by continuously being triggered by API activity.
The AppInit DLL functionality is disabled in Windows 8 and later versions when secure boot is enabled.(Citation: AppInit Secure Boot)
T1546.011
PersistencePrivilege Escalation
Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by application shims. The Microsoft Windows Application Compatibility Infrastructure/Framework (Application Shim) was created to allow for backward compatibility of software as the operating system codebase changes over time. For example, the application shimming feature allows developers to apply fixes to applications (without rewriting code) that were created for Windows XP so that they will work with Windows 10.(Citation: Elastic Process Injection July 2017)
Within the framework, shims are created to act as a buffer between the program (or more specifically, the Import Address Table) and the Windows OS. When a program is executed, the shim cache is referenced to determine if the program requires the use of the shim database (.sdb). If so, the shim database uses hooking to redirect the code as necessary in order to communicate with the OS.
A list of all shims currently installed by the default Windows installer (sdbinst.exe) is kept in:
* <code>%WINDIR%\AppPatch\sysmain.sdb</code> and
* <code>hklm\software\microsoft\windows nt\currentversion\appcompatflags\installedsdb</code>
Custom databases are stored in:
* <code>%WINDIR%\AppPatch\custom & %WINDIR%\AppPatch\AppPatch64\Custom</code> and
* <code>hklm\software\microsoft\windows nt\currentversion\appcompatflags\custom</code>
To keep shims secure, Windows designed them to run in user mode so they cannot modify the kernel and you must have administrator privileges to install a shim. However, certain shims can be used to [Bypass User Account Control](https://attack.mitre.org/techniques/T1548/002) (UAC and RedirectEXE), inject DLLs into processes (InjectDLL), disable Data Execution Prevention (DisableNX) and Structure Exception Handling (DisableSEH), and intercept memory addresses (GetProcAddress).
Utilizing these shims may allow an adversary to perform several malicious acts such as elevate privileges, install backdoors, disable defenses like Windows Defender, etc.(Citation: FireEye Application Shimming) Shims can also be abused to establish persistence by continuously being invoked by affected programs.
T1546.012
PersistencePrivilege Escalation
Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by Image File Execution Options (IFEO) debuggers. IFEOs enable a developer to attach a debugger to an application. When a process is created, a debugger present in an application’s IFEO will be prepended to the application’s name, effectively launching the new process under the debugger (e.g., <code>C:\dbg\ntsd.exe -g notepad.exe</code>).(Citation: Microsoft Dev Blog IFEO Mar 2010)
IFEOs can be set directly via the Registry or in Global Flags via the GFlags tool.(Citation: Microsoft GFlags Mar 2017) IFEOs are represented as <code>Debugger</code> values in the Registry under <code>HKLM\SOFTWARE{\Wow6432Node}\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\<executable></code> where <code><executable></code> is the binary on which the debugger is attached.(Citation: Microsoft Dev Blog IFEO Mar 2010)
IFEOs can also enable an arbitrary monitor program to be launched when a specified program silently exits (i.e. is prematurely terminated by itself or a second, non kernel-mode process).(Citation: Microsoft Silent Process Exit NOV 2017)(Citation: Oddvar Moe IFEO APR 2018) Similar to debuggers, silent exit monitoring can be enabled through GFlags and/or by directly modifying IFEO and silent process exit Registry values in <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\</code>.(Citation: Microsoft Silent Process Exit NOV 2017)(Citation: Oddvar Moe IFEO APR 2018)
Similar to [Accessibility Features](https://attack.mitre.org/techniques/T1546/008), on Windows Vista and later as well as Windows Server 2008 and later, a Registry key may be modified that configures "cmd.exe," or another program that provides backdoor access, as a "debugger" for an accessibility program (ex: utilman.exe). After the Registry is modified, pressing the appropriate key combination at the login screen while at the keyboard or when connected with [Remote Desktop Protocol](https://attack.mitre.org/techniques/T1021/001) will cause the "debugger" program to be executed with SYSTEM privileges.(Citation: Tilbury 2014)
Similar to [Process Injection](https://attack.mitre.org/techniques/T1055), these values may also be abused to obtain privilege escalation by causing a malicious executable to be loaded and run in the context of separate processes on the computer.(Citation: Elastic Process Injection July 2017) Installing IFEO mechanisms may also provide Persistence via continuous triggered invocation.
Malware may also use IFEO to impair defenses by registering invalid debuggers that redirect and effectively disable various system and security applications.(Citation: FSecure Hupigon)(Citation: Symantec Ushedix June 2008)
T1546.013
PersistencePrivilege Escalation
Adversaries may gain persistence and elevate privileges by executing malicious content triggered by PowerShell profiles. A PowerShell profile (<code>profile.ps1</code>) is a script that runs when [PowerShell](https://attack.mitre.org/techniques/T1059/001) starts and can be used as a logon script to customize user environments.
[PowerShell](https://attack.mitre.org/techniques/T1059/001) supports several profiles depending on the user or host program. For example, there can be different profiles for [PowerShell](https://attack.mitre.org/techniques/T1059/001) host programs such as the PowerShell console, PowerShell ISE or Visual Studio Code. An administrator can also configure a profile that applies to all users and host programs on the local computer.(Citation: Microsoft About Profiles)
Adversaries may modify these profiles to include arbitrary commands, functions, modules, and/or [PowerShell](https://attack.mitre.org/techniques/T1059/001) drives to gain persistence. Every time a user opens a [PowerShell](https://attack.mitre.org/techniques/T1059/001) session the modified script will be executed unless the <code>-NoProfile</code> flag is used when it is launched.(Citation: ESET Turla PowerShell May 2019)
An adversary may also be able to escalate privileges if a script in a PowerShell profile is loaded and executed by an account with higher privileges, such as a domain administrator.(Citation: Wits End and Shady PowerShell Profiles)
T1546.014
PersistencePrivilege Escalation
Adversaries may gain persistence and elevate privileges by executing malicious content triggered by the Event Monitor Daemon (emond). Emond is a [Launch Daemon](https://attack.mitre.org/techniques/T1543/004) that accepts events from various services, runs them through a simple rules engine, and takes action. The emond binary at <code>/sbin/emond</code> will load any rules from the <code>/etc/emond.d/rules/</code> directory and take action once an explicitly defined event takes place.
The rule files are in the plist format and define the name, event type, and action to take. Some examples of event types include system startup and user authentication. Examples of actions are to run a system command or send an email. The emond service will not launch if there is no file present in the QueueDirectories path <code>/private/var/db/emondClients</code>, specified in the [Launch Daemon](https://attack.mitre.org/techniques/T1543/004) configuration file at<code>/System/Library/LaunchDaemons/com.apple.emond.plist</code>.(Citation: xorrior emond Jan 2018)(Citation: magnusviri emond Apr 2016)(Citation: sentinelone macos persist Jun 2019)
Adversaries may abuse this service by writing a rule to execute commands when a defined event occurs, such as system startup or user authentication.(Citation: xorrior emond Jan 2018)(Citation: magnusviri emond Apr 2016)(Citation: sentinelone macos persist Jun 2019) Adversaries may also be able to escalate privileges from administrator to root as the emond service is executed with root privileges by the [Launch Daemon](https://attack.mitre.org/techniques/T1543/004) service.
T1546.015
PersistencePrivilege Escalation
Adversaries may establish persistence by executing malicious content triggered by hijacked references to Component Object Model (COM) objects. COM is a system within Windows to enable interaction between software components through the operating system.(Citation: Microsoft Component Object Model) References to various COM objects are stored in the Registry.
Adversaries may use the COM system to insert malicious code that can be executed in place of legitimate software through hijacking the COM references and relationships as a means for persistence. Hijacking a COM object requires a change in the Registry to replace a reference to a legitimate system component which may cause that component to not work when executed. When that system component is executed through normal system operation the adversary's code will be executed instead.(Citation: GDATA COM Hijacking) An adversary is likely to hijack objects that are used frequently enough to maintain a consistent level of persistence, but are unlikely to break noticeable functionality within the system as to avoid system instability that could lead to detection.
One variation of COM hijacking involves abusing Type Libraries (TypeLibs), which provide metadata about COM objects, such as their interfaces and methods. Adversaries may modify Registry keys associated with TypeLibs to redirect legitimate COM object functionality to malicious scripts or payloads. Unlike traditional COM hijacking, which commonly uses local DLLs, this variation may leverage the "script:" moniker to execute remote scripts hosted on external servers.(Citation: RELIAQUEST) This approach enables stealthy execution of code while maintaining persistence, as the remote payload would be automatically downloaded whenever the hijacked COM object is accessed.
T1546.016
PersistencePrivilege Escalation
Adversaries may establish persistence and elevate privileges by using an installer to trigger the execution of malicious content. Installer packages are OS specific and contain the resources an operating system needs to install applications on a system. Installer packages can include scripts that run prior to installation as well as after installation is complete. Installer scripts may inherit elevated permissions when executed. Developers often use these scripts to prepare the environment for installation, check requirements, download dependencies, and remove files after installation.(Citation: Installer Package Scripting Rich Trouton)
Using legitimate applications, adversaries have distributed applications with modified installer scripts to execute malicious content. When a user installs the application, they may be required to grant administrative permissions to allow the installation. At the end of the installation process of the legitimate application, content such as macOS `postinstall` scripts can be executed with the inherited elevated permissions. Adversaries can use these scripts to execute a malicious executable or install other malicious components (such as a [Launch Daemon](https://attack.mitre.org/techniques/T1543/004)) with the elevated permissions.(Citation: Application Bundle Manipulation Brandon Dalton)(Citation: wardle evilquest parti)(Citation: Windows AppleJeus GReAT)(Citation: Debian Manual Maintainer Scripts)
Depending on the distribution, Linux versions of package installer scripts are sometimes called maintainer scripts or post installation scripts. These scripts can include `preinst`, `postinst`, `prerm`, `postrm` scripts and run as root when executed.
For Windows, the Microsoft Installer service uses `.msi` files to manage the installing, updating, and uninstalling of applications. These installation routines may also include instructions to perform additional actions that may be abused by adversaries.(Citation: Microsoft Installation Procedures)
T1546.017
PersistencePrivilege Escalation
Adversaries may maintain persistence through executing malicious content triggered using udev rules. Udev is the Linux kernel device manager that dynamically manages device nodes, handles access to pseudo-device files in the `/dev` directory, and responds to hardware events, such as when external devices like hard drives or keyboards are plugged in or removed. Udev uses rule files with `match keys` to specify the conditions a hardware event must meet and `action keys` to define the actions that should follow. Root permissions are required to create, modify, or delete rule files located in `/etc/udev/rules.d/`, `/run/udev/rules.d/`, `/usr/lib/udev/rules.d/`, `/usr/local/lib/udev/rules.d/`, and `/lib/udev/rules.d/`. Rule priority is determined by both directory and by the digit prefix in the rule filename.(Citation: Ignacio Udev research 2024)(Citation: Elastic Linux Persistence 2024)
Adversaries may abuse the udev subsystem by adding or modifying rules in udev rule files to execute malicious content. For example, an adversary may configure a rule to execute their binary each time the pseudo-device file, such as `/dev/random`, is accessed by an application. Although udev is limited to running short tasks and is restricted by systemd-udevd's sandbox (blocking network and filesystem access), attackers may use scripting commands under the action key `RUN+=` to detach and run the malicious content’s process in the background to bypass these controls.(Citation: Reichert aon sedexp 2024)
T1546.018
PersistencePrivilege Escalation
Adversaries may achieve persistence by leveraging Python’s startup mechanisms, including path configuration (`.pth`) files and the `sitecustomize.py` or `usercustomize.py` modules. These files are automatically processed during the initialization of the Python interpreter, allowing for the execution of arbitrary code whenever Python is invoked.(Citation: Volexity GlobalProtect CVE 2024)
Path configuration files are designed to extend Python’s module search paths through the use of import statements. If a `.pth` file is placed in Python's `site-packages` or `dist-packages` directories, any lines beginning with `import` will be executed automatically on Python invocation.(Citation: DFIR Python Persistence 2025) Similarly, if `sitecustomize.py` or `usercustomize.py` is present in the Python path, these files will be imported during interpreter startup, and any code they contain will be executed.(Citation: Python Site Configuration Hook)
Adversaries may abuse these mechanisms to establish persistence on systems where Python is widely used (e.g., for automation or scripting in production environments).
T1547
PersistencePrivilege Escalation
Adversaries may configure system settings to automatically execute a program during system boot or logon to maintain persistence or gain higher-level privileges on compromised systems. Operating systems may have mechanisms for automatically running a program on system boot or account logon.(Citation: Microsoft Run Key)(Citation: MSDN Authentication Packages)(Citation: Microsoft TimeProvider)(Citation: Cylance Reg Persistence Sept 2013)(Citation: Linux Kernel Programming) These mechanisms may include automatically executing programs that are placed in specially designated directories or are referenced by repositories that store configuration information, such as the Windows Registry. An adversary may achieve the same goal by modifying or extending features of the kernel.
Since some boot or logon autostart programs run with higher privileges, an adversary may leverage these to elevate privileges.
T1547.001
PersistencePrivilege Escalation
Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. Adding an entry to the "run keys" in the Registry or startup folder will cause the program referenced to be executed when a user logs in.(Citation: Microsoft Run Key) These programs will be executed under the context of the user and will have the account's associated permissions level.
The following run keys are created by default on Windows systems:
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce</code>
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run</code>
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce</code>
Run keys may exist under multiple hives.(Citation: Microsoft Wow6432Node 2018)(Citation: Malwarebytes Wow6432Node 2016) The <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnceEx</code> is also available but is not created by default on Windows Vista and newer. Registry run key entries can reference programs directly or list them as a dependency.(Citation: Microsoft Run Key) For example, it is possible to load a DLL at logon using a "Depend" key with RunOnceEx: <code>reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnceEx\0001\Depend /v 1 /d "C:\temp\evil[.]dll"</code>(Citation: Oddvar Moe RunOnceEx Mar 2018)
Placing a program within a startup folder will also cause that program to execute when a user logs in. There is a startup folder location for individual user accounts as well as a system-wide startup folder that will be checked regardless of which user account logs in. The startup folder path for the current user is <code>C:\Users\\[Username]\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup</code>. The startup folder path for all users is <code>C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp</code>.
The following Registry keys can be used to set startup folder items for persistence:
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders</code>
* <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders</code>
* <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders</code>
The following Registry keys can control automatic startup of services during boot:
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServicesOnce</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServicesOnce</code>
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServices</code>
Using policy settings to specify startup programs creates corresponding values in either of two Registry keys:
* <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run</code>
* <code>HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run</code>
Programs listed in the load value of the registry key <code>HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows</code> run automatically for the currently logged-on user.
By default, the multistring <code>BootExecute</code> value of the registry key <code>HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager</code> is set to <code>autocheck autochk *</code>. This value causes Windows, at startup, to check the file-system integrity of the hard disks if the system has been shut down abnormally. Adversaries can add other programs or processes to this registry value which will automatically launch at boot.
Adversaries can use these configuration locations to execute malware, such as remote access tools, to maintain persistence through system reboots. Adversaries may also use [Masquerading](https://attack.mitre.org/techniques/T1036) to make the Registry entries look as if they are associated with legitimate programs.
T1547.002
PersistencePrivilege Escalation
Adversaries may abuse authentication packages to execute DLLs when the system boots. Windows authentication package DLLs are loaded by the Local Security Authority (LSA) process at system start. They provide support for multiple logon processes and multiple security protocols to the operating system.(Citation: MSDN Authentication Packages)
Adversaries can use the autostart mechanism provided by LSA authentication packages for persistence by placing a reference to a binary in the Windows Registry location <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\</code> with the key value of <code>"Authentication Packages"=<target binary></code>. The binary will then be executed by the system when the authentication packages are loaded.
T1547.003
PersistencePrivilege Escalation
Adversaries may abuse time providers to execute DLLs when the system boots. The Windows Time service (W32Time) enables time synchronization across and within domains.(Citation: Microsoft W32Time Feb 2018) W32Time time providers are responsible for retrieving time stamps from hardware/network resources and outputting these values to other network clients.(Citation: Microsoft TimeProvider)
Time providers are implemented as dynamic-link libraries (DLLs) that are registered in the subkeys of `HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\W32Time\TimeProviders\`.(Citation: Microsoft TimeProvider) The time provider manager, directed by the service control manager, loads and starts time providers listed and enabled under this key at system startup and/or whenever parameters are changed.(Citation: Microsoft TimeProvider)
Adversaries may abuse this architecture to establish persistence, specifically by creating a new arbitrarily named subkey pointing to a malicious DLL in the `DllName` value. Administrator privileges are required for time provider registration, though execution will run in context of the Local Service account.(Citation: Github W32Time Oct 2017)
T1547.004
PersistencePrivilege Escalation
Adversaries may abuse features of Winlogon to execute DLLs and/or executables when a user logs in. Winlogon.exe is a Windows component responsible for actions at logon/logoff as well as the secure attention sequence (SAS) triggered by Ctrl-Alt-Delete. Registry entries in <code>HKLM\Software[\\Wow6432Node\\]\Microsoft\Windows NT\CurrentVersion\Winlogon\</code> and <code>HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\</code> are used to manage additional helper programs and functionalities that support Winlogon.(Citation: Cylance Reg Persistence Sept 2013)
Malicious modifications to these Registry keys may cause Winlogon to load and execute malicious DLLs and/or executables. Specifically, the following subkeys have been known to be possibly vulnerable to abuse:(Citation: Cylance Reg Persistence Sept 2013)
* Winlogon\Notify - points to notification package DLLs that handle Winlogon events
* Winlogon\Userinit - points to userinit.exe, the user initialization program executed when a user logs on
* Winlogon\Shell - points to explorer.exe, the system shell executed when a user logs on
Adversaries may take advantage of these features to repeatedly execute malicious code and establish persistence.
T1547.005
PersistencePrivilege Escalation
Adversaries may abuse security support providers (SSPs) to execute DLLs when the system boots. Windows SSP DLLs are loaded into the Local Security Authority (LSA) process at system start. Once loaded into the LSA, SSP DLLs have access to encrypted and plaintext passwords that are stored in Windows, such as any logged-on user's Domain password or smart card PINs.
The SSP configuration is stored in two Registry keys: <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Security Packages</code> and <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\OSConfig\Security Packages</code>. An adversary may modify these Registry keys to add new SSPs, which will be loaded the next time the system boots, or when the AddSecurityPackage Windows API function is called.(Citation: Graeber 2014)
T1547.006
PersistencePrivilege Escalation
Adversaries may modify the kernel to automatically execute programs on system boot. Loadable Kernel Modules (LKMs) are pieces of code that can be loaded and unloaded into the kernel upon demand. They extend the functionality of the kernel without the need to reboot the system. For example, one type of module is the device driver, which allows the kernel to access hardware connected to the system.(Citation: Linux Kernel Programming)
When used maliciously, LKMs can be a type of kernel-mode [Rootkit](https://attack.mitre.org/techniques/T1014) that run with the highest operating system privilege (Ring 0).(Citation: Linux Kernel Module Programming Guide) Common features of LKM based rootkits include: hiding itself, selective hiding of files, processes and network activity, as well as log tampering, providing authenticated backdoors, and enabling root access to non-privileged users.(Citation: iDefense Rootkit Overview)
Kernel extensions, also called kext, are used in macOS to load functionality onto a system similar to LKMs for Linux. Since the kernel is responsible for enforcing security and the kernel extensions run as apart of the kernel, kexts are not governed by macOS security policies. Kexts are loaded and unloaded through <code>kextload</code> and <code>kextunload</code> commands. Kexts need to be signed with a developer ID that is granted privileges by Apple allowing it to sign Kernel extensions. Developers without these privileges may still sign kexts but they will not load unless SIP is disabled. If SIP is enabled, the kext signature is verified before being added to the AuxKC.(Citation: System and kernel extensions in macOS)
Since macOS Catalina 10.15, kernel extensions have been deprecated in favor of System Extensions. However, kexts are still allowed as "Legacy System Extensions" since there is no System Extension for Kernel Programming Interfaces.(Citation: Apple Kernel Extension Deprecation)
Adversaries can use LKMs and kexts to conduct [Persistence](https://attack.mitre.org/tactics/TA0003) and/or [Privilege Escalation](https://attack.mitre.org/tactics/TA0004) on a system. Examples have been found in the wild, and there are some relevant open source projects as well.(Citation: Volatility Phalanx2)(Citation: CrowdStrike Linux Rootkit)(Citation: GitHub Reptile)(Citation: GitHub Diamorphine)(Citation: RSAC 2015 San Francisco Patrick Wardle)(Citation: Synack Secure Kernel Extension Broken)(Citation: Securelist Ventir)(Citation: Trend Micro Skidmap)
T1547.007
PersistencePrivilege Escalation
Adversaries may modify plist files to automatically run an application when a user logs in. When a user logs out or restarts via the macOS Graphical User Interface (GUI), a prompt is provided to the user with a checkbox to "Reopen windows when logging back in".(Citation: Re-Open windows on Mac) When selected, all applications currently open are added to a property list file named <code>com.apple.loginwindow.[UUID].plist</code> within the <code>~/Library/Preferences/ByHost</code> directory.(Citation: Methods of Mac Malware Persistence)(Citation: Wardle Persistence Chapter) Applications listed in this file are automatically reopened upon the user’s next logon.
Adversaries can establish [Persistence](https://attack.mitre.org/tactics/TA0003) by adding a malicious application path to the <code>com.apple.loginwindow.[UUID].plist</code> file to execute payloads when a user logs in.
T1547.008
PersistencePrivilege Escalation
Adversaries may modify or add LSASS drivers to obtain persistence on compromised systems. The Windows security subsystem is a set of components that manage and enforce the security policy for a computer or domain. The Local Security Authority (LSA) is the main component responsible for local security policy and user authentication. The LSA includes multiple dynamic link libraries (DLLs) associated with various other security functions, all of which run in the context of the LSA Subsystem Service (LSASS) lsass.exe process.(Citation: Microsoft Security Subsystem)
Adversaries may target LSASS drivers to obtain persistence. By either replacing or adding illegitimate drivers (e.g., [Hijack Execution Flow](https://attack.mitre.org/techniques/T1574)), an adversary can use LSA operations to continuously execute malicious payloads.
T1547.009
PersistencePrivilege Escalation
Adversaries may create or modify shortcuts that can execute a program during system boot or user login. Shortcuts or symbolic links are used to reference other files or programs that will be opened or executed when the shortcut is clicked or executed by a system startup process.
Adversaries may abuse shortcuts in the startup folder to execute their tools and achieve persistence.(Citation: Shortcut for Persistence ) Although often used as payloads in an infection chain (e.g. [Spearphishing Attachment](https://attack.mitre.org/techniques/T1566/001)), adversaries may also create a new shortcut as a means of indirection, while also abusing [Masquerading](https://attack.mitre.org/techniques/T1036) to make the malicious shortcut appear as a legitimate program. Adversaries can also edit the target path or entirely replace an existing shortcut so their malware will be executed instead of the intended legitimate program.
Shortcuts can also be abused to establish persistence by implementing other methods. For example, LNK browser extensions may be modified (e.g. [Browser Extensions](https://attack.mitre.org/techniques/T1176/001)) to persistently launch malware.
T1547.010
PersistencePrivilege Escalation
Adversaries may use port monitors to run an adversary supplied DLL during system boot for persistence or privilege escalation. A port monitor can be set through the <code>AddMonitor</code> API call to set a DLL to be loaded at startup.(Citation: AddMonitor) This DLL can be located in <code>C:\Windows\System32</code> and will be loaded and run by the print spooler service, `spoolsv.exe`, under SYSTEM level permissions on boot.(Citation: Bloxham)
Alternatively, an arbitrary DLL can be loaded if permissions allow writing a fully-qualified pathname for that DLL to the `Driver` value of an existing or new arbitrarily named subkey of <code>HKLM\SYSTEM\CurrentControlSet\Control\Print\Monitors</code>. The Registry key contains entries for the following:
* Local Port
* Standard TCP/IP Port
* USB Monitor
* WSD Port
T1547.011
PersistencePrivilege Escalation
Adversaries can modify property list files (plist files) to execute their code as part of establishing persistence. Plist files are used by macOS applications to store properties and configuration settings for applications and services. Applications use information plist files, <code>Info.plist</code>, to tell the operating system how to handle the application at runtime using structured metadata in the form of keys and values. Plist files are formatted in XML and based on Apple's Core Foundation DTD and can be saved in text or binary format.(Citation: fileinfo plist file description)
Adversaries can modify paths to executed binaries, add command line arguments, and insert key/pair values to plist files in auto-run locations which execute upon user logon or system startup. Through modifying plist files in these locations, adversaries can also execute a malicious dynamic library (dylib) by adding a dictionary containing the <code>DYLD_INSERT_LIBRARIES</code> key combined with a path to a malicious dylib under the <code>EnvironmentVariables</code> key in a plist file. Upon user logon, the plist is called for execution and the malicious dylib is executed within the process space. Persistence can also be achieved by modifying the <code>LSEnvironment</code> key in the application's <code>Info.plist</code> file.(Citation: wardle artofmalware volume1)
T1547.012
PersistencePrivilege Escalation
Adversaries may abuse print processors to run malicious DLLs during system boot for persistence and/or privilege escalation. Print processors are DLLs that are loaded by the print spooler service, `spoolsv.exe`, during boot.(Citation: Microsoft Intro Print Processors)
Adversaries may abuse the print spooler service by adding print processors that load malicious DLLs at startup. A print processor can be installed through the <code>AddPrintProcessor</code> API call with an account that has <code>SeLoadDriverPrivilege</code> enabled. Alternatively, a print processor can be registered to the print spooler service by adding the <code>HKLM\SYSTEM\\[CurrentControlSet or ControlSet001]\Control\Print\Environments\\[Windows architecture: e.g., Windows x64]\Print Processors\\[user defined]\Driver</code> Registry key that points to the DLL.
For the malicious print processor to be correctly installed, the payload must be located in the dedicated system print-processor directory, that can be found with the <code>GetPrintProcessorDirectory</code> API call, or referenced via a relative path from this directory.(Citation: Microsoft AddPrintProcessor May 2018) After the print processors are installed, the print spooler service, which starts during boot, must be restarted in order for them to run.(Citation: ESET PipeMon May 2020)
The print spooler service runs under SYSTEM level permissions; therefore, print processors installed by an adversary may run under elevated privileges.
T1547.013
PersistencePrivilege Escalation
Adversaries may add or modify XDG Autostart Entries to execute malicious programs or commands when a user’s desktop environment is loaded at login. XDG Autostart entries are available for any XDG-compliant Linux system. XDG Autostart entries use Desktop Entry files (`.desktop`) to configure the user’s desktop environment upon user login. These configuration files determine what applications launch upon user login, define associated applications to open specific file types, and define applications used to open removable media.(Citation: Free Desktop Application Autostart Feb 2006)(Citation: Free Desktop Entry Keys)
Adversaries may abuse this feature to establish persistence by adding a path to a malicious binary or command to the `Exec` directive in the `.desktop` configuration file. When the user’s desktop environment is loaded at user login, the `.desktop` files located in the XDG Autostart directories are automatically executed. System-wide Autostart entries are located in the `/etc/xdg/autostart` directory while the user entries are located in the `~/.config/autostart` directory.
Adversaries may combine this technique with [Masquerading](https://attack.mitre.org/techniques/T1036) to blend malicious Autostart entries with legitimate programs.(Citation: Red Canary Netwire Linux 2022)
T1547.014
PersistencePrivilege Escalation
Adversaries may achieve persistence by adding a Registry key to the Active Setup of the local machine. Active Setup is a Windows mechanism that is used to execute programs when a user logs in. The value stored in the Registry key will be executed after a user logs into the computer.(Citation: Klein Active Setup 2010) These programs will be executed under the context of the user and will have the account's associated permissions level.
Adversaries may abuse Active Setup by creating a key under <code> HKLM\SOFTWARE\Microsoft\Active Setup\Installed Components\</code> and setting a malicious value for <code>StubPath</code>. This value will serve as the program that will be executed when a user logs into the computer.(Citation: Mandiant Glyer APT 2010)(Citation: Citizenlab Packrat 2015)(Citation: FireEye CFR Watering Hole 2012)(Citation: SECURELIST Bright Star 2015)(Citation: paloalto Tropic Trooper 2016)
Adversaries can abuse these components to execute malware, such as remote access tools, to maintain persistence through system reboots. Adversaries may also use [Masquerading](https://attack.mitre.org/techniques/T1036) to make the Registry entries look as if they are associated with legitimate programs.
T1547.015
PersistencePrivilege Escalation
Adversaries may add login items to execute upon user login to gain persistence or escalate privileges. Login items are applications, documents, folders, or server connections that are automatically launched when a user logs in.(Citation: Open Login Items Apple) Login items can be added via a shared file list or Service Management Framework.(Citation: Adding Login Items) Shared file list login items can be set using scripting languages such as [AppleScript](https://attack.mitre.org/techniques/T1059/002), whereas the Service Management Framework uses the API call <code>SMLoginItemSetEnabled</code>.
Login items installed using the Service Management Framework leverage <code>launchd</code>, are not visible in the System Preferences, and can only be removed by the application that created them.(Citation: Adding Login Items)(Citation: SMLoginItemSetEnabled Schroeder 2013) Login items created using a shared file list are visible in System Preferences, can hide the application when it launches, and are executed through LaunchServices, not launchd, to open applications, documents, or URLs without using Finder.(Citation: Launch Services Apple Developer) Users and applications use login items to configure their user environment to launch commonly used services or applications, such as email, chat, and music applications.
Adversaries can utilize [AppleScript](https://attack.mitre.org/techniques/T1059/002) and [Native API](https://attack.mitre.org/techniques/T1106) calls to create a login item to spawn malicious executables.(Citation: ELC Running at startup) Prior to version 10.5 on macOS, adversaries can add login items by using [AppleScript](https://attack.mitre.org/techniques/T1059/002) to send an Apple event to the “System Events” process, which has an AppleScript dictionary for manipulating login items.(Citation: Login Items AE) Adversaries can use a command such as <code>tell application “System Events” to make login item at end with properties /path/to/executable</code>.(Citation: Startup Items Eclectic)(Citation: hexed osx.dok analysis 2019)(Citation: Add List Remove Login Items Apple Script) This command adds the path of the malicious executable to the login item file list located in <code>~/Library/Application Support/com.apple.backgroundtaskmanagementagent/backgrounditems.btm</code>.(Citation: Startup Items Eclectic) Adversaries can also use login items to launch executables that can be used to control the victim system remotely or as a means to gain privilege escalation by prompting for user credentials.(Citation: objsee mac malware 2017)(Citation: CheckPoint Dok)(Citation: objsee netwire backdoor 2019)
T1554
Persistence
Adversaries may modify host software binaries to establish persistent access to systems. Software binaries/executables provide a wide range of system commands or services, programs, and libraries. Common software binaries are SSH clients, FTP clients, email clients, web browsers, and many other user or server applications.
Adversaries may establish persistence through modifications to host software binaries. For example, an adversary may replace or otherwise infect a legitimate application binary (or support files) with a backdoor. Since these binaries may be routinely executed by applications or the user, the adversary can leverage this for persistent access to the host. An adversary may also modify a software binary such as an SSH client in order to persistently collect credentials during logins (i.e., [Modify Authentication Process](https://attack.mitre.org/techniques/T1556)).(Citation: Google Cloud Mandiant UNC3886 2024)
An adversary may also modify an existing binary by patching in malicious functionality (e.g., IAT Hooking/Entry point patching)(Citation: Unit42 Banking Trojans Hooking 2022) prior to the binary’s legitimate execution. For example, an adversary may modify the entry point of a binary to point to malicious code patched in by the adversary before resuming normal execution flow.(Citation: ESET FontOnLake Analysis 2021)
After modifying a binary, an adversary may attempt to impair defenses by preventing it from updating (e.g., via the `yum-versionlock` command or `versionlock.list` file in Linux systems that use the yum package manager).(Citation: Google Cloud Mandiant UNC3886 2024)