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Microsoft Internet Explorer Use After Free Vulnerability

04.10.12

BACKGROUND

Internet Explorer is a graphical web browser developed by Microsoft Corp. that has been included with Microsoft Windows since 1995. For more information about Internet Explorer, please the visit following website: http://www.microsoft.com/windows/internet-explorer/default.aspx

DESCRIPTION

Remote exploitation of a use-after-free vulnerability in Microsoft Corp.'s Internet Explorer could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability is triggered when the 'innerHTML' property of the body element is dynamically modified via JavaScript code. When this occurs, a certain object that represents the document is freed; however, a reference to it remains. This reference is later reused, which can lead to stale data being accessed. This leads to the execution of arbitrary code.

ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user viewing the web page. To exploit this vulnerability, a targeted user must load a malicious webpage created by an attacker. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites. After the user visits the malicious web page, no further user interaction is needed.

DETECTION

Microsoft Internet Explorer 6 and 7 are vulnerable.

WORKAROUND

Microsoft suggested workarounds can be found under the workaround section of the following link:

http://technet.microsoft.com/en-us/security/bulletin/ms12-023

VENDOR RESPONSE

Microsoft has released updates to address this vulnerability. For more information, consult their advisory at the following URL.

http://technet.microsoft.com/en-us/security/bulletin/ms12-023

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-0170 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

12/07/2011 Initial Vendor Notification
12/07/2011 Initial Vendor Reply
04/10/2011 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by Jose A. Vazquez of http://spa-s3c.blogspot.com.

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LEGAL NOTICES

Copyright © 2012 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.