Microsoft Internet Explorer CHTML code execution

Notification Type: IBM Security Protection Advisory
Notification Date: February 12, 2013
Notification Version: 1.0
Name: Microsoft Internet Explorer CHTML code execution
Public disclosure/
In the wild date:
February 12, 2013
Aliases: MS13-009
CVE: CVE-2013-0029

Microsoft Internet Explorer is vulnerable to a use-after-free condition which can lead to remote code execution.

Discoverer: This vulnerability was discovered and researched by Mark Yason of IBM X-Force.


ISS Coverage

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

Remote exploit

HTML_Focus_Attack *
08 Jan 2013
* This signature is blocking by default.

Detailed Description

Business Impact:

Compromise of machines using affected versions of Microsoft 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.  A successful exploitation attempt results in code execution with privileges equal to Internet Explorer’s privileges.

*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: 6.9
  Exploitability: Unproven
Remediation Level: Official-Fix
Report Confidence: Confirmed
Affected Products:

See References for details.

Technical Description:

The vulnerability is due to a failure in maintaining a correct reference count of an object. Because of an incorrect reference count, an attacker can force the freeing of an object currently in use and then reallocate the memory previously allocated for the freed object to contain an attacker-controlled data. This could result in arbitrary code execution when the freed object is later accessed.


Apply the appropriate patch for your system, as listed in Microsoft Security Bulletin MS13-009. See References.



Revision History

1.0 Initial publication.

* According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.
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