Some video drivers fail to support ASLR in Microsoft EMET "Always on" mode, which can limit the amount that such a system can be secured.
ASLR, when combined with DEP (Data Execution Prevention) can be an effective mitigation against exploitation of vulnerabilities. For more information about DEP and ASLR on Microsoft Windows platforms, see the Microsoft Security Research & Defense blog entry: On the effectiveness of DEP and ASLR. Microsoft has released a tool called EMET (Exploit Mitigation Experience Toolkit) to enforce DEP, ASLR, and other exploit mitigation features for Windows systems on an application-specific and a system-wide basis. DEP and ASLR features are available on other operating systems as well.
Some video drivers are not compatible with the Microsoft EMET "Always on" mode for ASLR. Enabling "Always on" ASLR on a system with incompatible video drivers may result in a system crash (kernel panic, or BSOD).
Problems have also been reported using ATI drivers on Linux systems using PaX.
Systems with incompatible video drivers cannot be secured as well as those with ASLR-compatible drivers. Enabling system-wide DEP and ASLR can make exploitation of vulnerabilities more difficult.
Apply an update
AMD has released Catalyst drivers version 12.6 for supported Radeon hardware; these drivers are compatible with system-wide ASLR. If you are unable to obtain updated drivers, please consider the following workarounds.
Use standard VGA drivers
On systems where video performance is not a requirement (servers, for example), the use of standard VGA drivers can allow the use of EMET "Always on" ASLR.
Use a different video adapter
If the video adapter on your system is not compatible with EMET "Always on" ASLR, consider using a different video adapter that has ASLR compatible drivers.
Vendor| Status| Date Notified| Date Updated
AMD| | 16 Feb 2012| 29 Jun 2012
ATI Technologies| | -| 05 Jun 2012
Intel Corporation| | 01 Jun 2012| 05 Jun 2012
NVIDIA| | 01 Jun 2012| 05 Jun 2012
If you are a vendor and your product is affected, let us know.
Group | Score | Vector
Base | 0.0 | AV:--/AC:--/Au:--/C:--/I:--/A:--
Temporal | 0.0 | E:--/RL:OF/RC:C
Environmental | 0.0 | CDP:ND/TD:H/CR:ND/IR:ND/AR:ND
This document was written by Will Dormann.