T1546.008: Accessibility Features — MITRE ATT&CK Technique

Description

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

Platforms

Windows

Mitigations (3)

Limit Access to Resource Over NetworkM1035

If possible, use a Remote Desktop Gateway to manage connections and security configuration of RDP within a network.(Citation: TechNet RDP Gateway)

Operating System ConfigurationM1028

To use this technique remotely, an adversary must use it in conjunction with RDP. Ensure that Network Level Authentication is enabled to force the remote desktop session to authenticate before the session is created and the login screen displayed. It is enabled by default on Windows Vista and later.(Citation: TechNet RDP NLA)

Execution PreventionM1038

Adversaries can replace accessibility features binaries with alternate binaries to execute this technique. Identify and block potentially malicious software executed through accessibility features functionality by using application control (Citation: Beechey 2010) tools, like Windows Defender Application Control(Citation: Microsoft Windows Defender Application Control), AppLocker, (Citation: Windo

Threat Groups (6)

ID	Group	Context
G0096	APT41	[APT41](https://attack.mitre.org/groups/G0096) leveraged sticky keys to establish persistence.(Citation: FireEye APT41 Aug 2019)
G0022	APT3	[APT3](https://attack.mitre.org/groups/G0022) replaces the Sticky Keys binary <code>C:\Windows\System32\sethc.exe</code> for persistence.(Citation: ap...
G0009	Deep Panda	[Deep Panda](https://attack.mitre.org/groups/G0009) has used the sticky-keys technique to bypass the RDP login screen on remote systems during intrusi...
G0001	Axiom	[Axiom](https://attack.mitre.org/groups/G0001) actors have been known to use the Sticky Keys replacement within RDP sessions to obtain persistence.(Ci...
G0117	Fox Kitten	[Fox Kitten](https://attack.mitre.org/groups/G0117) has used sticky keys to launch a command prompt.(Citation: CISA AA20-259A Iran-Based Actor Septemb...
G0016	APT29	[APT29](https://attack.mitre.org/groups/G0016) used sticky-keys to obtain unauthenticated, privileged console access.(Citation: Mandiant No Easy Breac...

Associated Software (1)

ID	Name	Type	Context
S0363	Empire	Tool	[Empire](https://attack.mitre.org/software/S0363) can leverage WMI debugging to remotely replace binaries like sethc.exe, Utilman.exe, and Magnify.exe...

References

Frequently Asked Questions

What is T1546.008 (Accessibility Features)?

T1546.008 is a MITRE ATT&CK technique named 'Accessibility Features'. It belongs to the Privilege Escalation, Persistence tactic(s). 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...

How can T1546.008 be detected?

Detection of T1546.008 (Accessibility Features) typically involves monitoring system logs, network traffic, and endpoint telemetry. Use SIEM rules, EDR solutions, and behavioral analytics to identify suspicious activity associated with this technique.

What mitigations exist for T1546.008?

There are 3 documented mitigations for T1546.008. Key mitigations include: Limit Access to Resource Over Network, Operating System Configuration, Execution Prevention.

Which threat groups use T1546.008?

Known threat groups using T1546.008 include: APT41, APT3, Deep Panda, Axiom, Fox Kitten, APT29.