Google Researcher Unveils Windows 8.1 Security Flaw

security flaw in windows 8.1

Google researcher 'forshaw' have discovered and reported a privilege escalation vulnerability in windows 8.1. Forshaw also released a Proof Of Concept program for the vulnerability:

The PoC has been tested on Windows 8.1 update, both 32 bit and 64 bit versions. I'd recommend running on 32 bit just to be sure. To verify perform the following steps: 

1) Put the AppCompatCache.exe and Testdll.dll on disk
2) Ensure that UAC is enabled, the current user is a split-token admin and the UAC setting is the default (no prompt for specific executables).
3) Execute AppCompatCache from the command prompt with the command line "AppCompatCache.exe c:\windows\system32\ComputerDefaults.exe testdll.dll".
4) If successful then the calculator should appear running as an administrator. If it doesn't work first time (and you get the ComputerDefaults program) re-run the exploit from 3, there seems to be a caching/timing issue sometimes on first run.
This bug is subject to a 90 day disclosure deadline. If 90 days elapse without a broadly available patch, then the bug report will automatically become visible to the public.


A Microsoft spokesperson responded to this threat - "We are working to release a security update to address an Elevation of Privilege issue. It is important to note that for a would-be attacker to potentially exploit a system, they would first need to have valid logon credentials and be able to log on locally to a targeted machine. We encourage customers to keep their anti-virus software up to date, install all available Security Updates and enable the firewall on their computer."

image credit : blogs.windows.com

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