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IE 8/9 mshtml.dll NULL_IMPORT_DESCRIPTOR Use After Free

Disclosed September 17, 2013    Fully Patched, Workaround Available

Vulnerability Description:

There is a use after free in Internet Explorer, that when combined with a non-ASLR Office DLL, can allow for remote code execution in the context of the currently logged on user. This attack has been spotted in the wild in Japan, in targeted attacks. The attack is not widespread yet. However, with the introduction of a Microsoft Fix it, attackers may be able to more easily deduce the vulnerability being targeted, and produce exploits.

Vendors:

Microsoft

Vulnerable Software/Devices:

Internet Explorer 6
Internet Explorer 7
Internet Explorer 8 (in the wild, targeted attacks focusing on XP and 7)
Internet Explorer 9 (in the wild, targeted attacks focusing on XP and 7)
Internet Explorer 10
Internet Explorer 11

Vulnerability Severity:

High

Exploit Availability:

Publicly Available

Exploit Impact:

Remote Code Execution
Exploitation of this vulnerability is possible through the use of methods like drive-by attacks. Remote attackers who successfully exploit this vulnerability will be able to execute code on the vulnerable system with the same rights as the currently logged on user.

BeyondTrust Prevention and Detection:

BeyondTrust's Retina® Network Security Scanner scans devices to detect for this vulnerability.

  • 30887 - Microsoft Internet Explorer Cumulative Security Update (2879017)
  • 30888 - Microsoft Internet Explorer Cumulative Security Update (2879017) - x64

Mitigation:

Apply the Microsoft Fix it immediately to prevent exploitation. Additionally, EMET 4.0 mitigates this attack. Otherwise, use other browsers such as Chrome.

Links: