Advisory Details

August 9th, 2011

(Pwn2Own) Microsoft Internet Explorer Protected Mode Bypass Vulnerability

ZDI-11-249
ZDI-CAN-1159

CVE ID CVE-2011-1347
CVSS SCORE 6.4, (AV:N/AC:L/Au:N/C:P/I:P/A:N)
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Internet Explorer
TREND MICRO CUSTOMER PROTECTION Trend Micro TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 11294. For further product information on the TippingPoint IPS: http://www.tippingpoint.com
VULNERABILITY DETAILS

This vulnerability allows remote attackers to escape Protected Mode on vulnerable installations of Internet Explorer.

Internet Explorer Protected Mode consists of a Medium Integrity and a Low Integrity process. The Low Integrity process is only allowed to write to special Low Integrity locations. File written there are marked as Low Integrity files. When a new Internet Explorer process is launched it checks the Integrity of the file it is launched against. If the file is a Low Integrity file it will run the process in Low Integrity Mode. It is however possible to give the file an even lower permission: Untrusted, since this does not match the check for 'Low Integrity' the Internet Explorer will run in Medium Integrity instead of Low Integrity. This can be abused in an exploit to bypass the Protected Mode design and thus allow an attacker to escalate their privileges.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
http://www.microsoft.com/technet/security/bulletin/MS11-057.mspx
DISCLOSURE TIMELINE
  • 2011-03-09 - Vulnerability reported to vendor
  • 2011-08-09 - Coordinated public release of advisory
CREDIT Stephen Fewer of Harmony Security (www.harmonysecurity.com)
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