Vigil@nce - Sophos AV: privilege elevation via SAVOnAccessFilter
June 2010 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/
SYNTHESIS OF THE VULNERABILITY
A local attacker can use a vulnerability of the SAVOnAccessFilter driver, in order to obtain system privileges.
Creation date: 10/06/2010
DESCRIPTION OF THE VULNERABILITY
The Sophos antivirus installs the SAVOnAccessFilter.sys driver, which checks system calls when they are used.
The NtQueryAttributesFile() system call retrieves information on a file. The SAVOnAccessFilter.sys driver checks this system call.
However, parameters of NtQueryAttributesFile() are not correctly filtered by the driver, which corrupts its memory.
A local attacker can therefore use a vulnerability of the SAVOnAccessFilter driver, in order to obtain system privileges.
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