T1546.008: Accessibility Features
| View on MITRE ATT&CK | T1546.008 |
|---|---|
| Tactic(s) | Persistence, Privilege Escalation |
| Associated CAPEC Patterns | Replace Trusted Executable (CAPEC-558) |
Data from MITRE ATT&CK®:
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 C:\Windows\System32\sethc.exe, launched when the shift key is pressed five times and C:\Windows\System32\utilman.exe, 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 %systemdir%\, and it must be protected by Windows File or Resource Protection (WFP/WRP). (Citation: DEFCON2016 Sticky Keys) The Image File Execution Options Injection 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 and Windows Server 2003/R2 and later, for example, the program (e.g., C:\Windows\System32\utilman.exe) 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 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:
C:\Windows\System32\osk.exe - Magnifier:
C:\Windows\System32\Magnify.exe - Narrator:
C:\Windows\System32\Narrator.exe - Display Switcher:
C:\Windows\System32\DisplaySwitch.exe - App Switcher:
C:\Windows\System32\AtBroker.exe
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Cyber Threat Graph Context
Explore how this ATT&CK Technique relates to the wider threat graph
Mitigations for this technique
MITRE ATT&CK Mitigations
Execution Prevention
Block execution of code on a system through application control, and/or script blocking.Limit Access to Resource Over Network
Prevent access to file shares, remote access to systems, unnecessary services. Mechanisms to limit access may include use of network concentrators, RDP gateways, etc.Operating System Configuration
Make configuration changes related to the operating system or a common feature of the operating system that result in system hardening against techniques.How to detect this technique
MITRE ATT&CK Data Components
File Creation (File)
Initial construction of a new file (ex: Sysmon EID 11)Process Creation (Process)
The initial construction of an executable managed by the OS, that may involve one or more tasks or threads. (e.g. Win EID 4688, Sysmon EID 1, cmd.exe > net use, etc.)Windows Registry Key Modification (Windows Registry)
Changes made to a Registry Key and/or Key value (ex: Windows EID 4657 or Sysmon EID 13|14)Command Execution (Command)
The execution of a line of text, potentially with arguments, created from program code (e.g. a cmdlet executed via powershell.exe, interactive commands like >dir, shell executions, etc. )File Modification (File)
Changes made to a file, or its access permissions and attributes, typically to alter the contents of the targeted file (ex: Windows EID 4670 or Sysmon EID 2)Control Validation Tests for this Technique
Use Atomic Red Team tests to test your defenses against this technique.
Sigma Detections for this Technique
Potential Suspicious Activity Using SeCEdit
Sticky Key Like Backdoor Execution
Potential Privilege Escalation Using Symlink Between Osk and Cmd
Potential Windows Defender Tampering Via Wmic.EXE
Suspicious Debugger Registration Cmdline
Persistence Via Sticky Key Backdoor
Sticky Key Like Backdoor Usage - Registry
SP800-53 Controls
See which controls can help protect against this MITRE ATT&CK technique. This is based on mappings to associated SP800-53 controls produced by the MITRE Engenuity Center for Threat-Informed Defense.