Microsoft Internet Explorer Use After Free Vulnerability

Notification Type: IBM Security Solutions Protection Alert
Notification Date: May 15, 2013
Notification Version: 1.0
Name: Microsoft Internet Explorer Use After Free Vulnerability
Public disclosure/
In the wild date:
May 03, 2013
Aliases: MS13-038
Risk: Critical
CVE: CVE-2013-1347

There is a use-after-free vulnerability affecting Microsoft Internet Explorer 8 (only ). The vulnerability came to light when it was used in a watering hole attack after a breach of a US Department of Labor (DoL) server. This vulnerability has been exploited in the wild by attackers to gain remote code execution in the context of the current user.


ISS Coverage

Product Content Version
Network Protection XGS
Proventia Network IDS
Proventia Network IPS
Proventia Network MFS
Proventia Server (Linux)
RealSecure Network
RealSecure Server Sensor
Proventia Desktop
Proventia Server IPS (Windows)
Propagation Techniques ISS Protection Available

remote exploit




15 May 2013

15 May 2013

14 Sep 2010

* These signatures are blocked in the default policy.

Additional note: Attacks exploiting this vulnerability and attacks exploiting CVE-2013-2551 are very similar in nature and are detected using the same events. Script_Suspicious_Score is also known to detect a particular exploit of CVE-2013-1347.

Detailed Description

Business Impact:

Compromise of networks and machines using affected versions of Internet Explorer may lead to exposure of confidential information, loss of productivity, and further network compromise. Remote code execution could be achieved by enticing a user to visit a specially crafted web page exploiting this vulnerability, either in HTML email messages or otherwise.

*CVSS Base Score: 9.3
  Access Vector: Network
Access Complexity: Medium
Authentication: None
Confidentiality Impact: Complete
Integrity Impact: Complete
Availability Impact: Complete
Adjusted Temporal Score: 7.7
  Exploitability: Functional
Remediation Level: Official-Fix
Report Confidence: Confirmed
Affected Products:

See References for details.

Technical Description:

This is a use-after-free CGenericElement object whereby the browser maintains a reference of the object even after it is freed. On subsequent rendering, this controllable memory is then used again, thus allowing arbitrary code execution. All that is required for a user to be exploited is to visit a page with malicious code. This vulnerability is actively being exploited in the wild, and Microsoft has released a FixIt (see references for link) for this issue. Affected users are strongly encouraged to apply the patch, or upgrade the browser as soon as possible.


A patch is available, see references below for details



Revision History

1.0 Initial publication.

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