Public Vulnerability Reports

Microsoft Internet Explorer Use-After-Free Memory Corruption Vulnerability

04.12.11

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 occurs when an object is exchanged during a call to a certain function. The object's memory is freed, however a reference to the object remains. When the reference is later used to access the object, this now invalid memory is treated as a valid object and one of the object members is used to make an indirect function call. This may result in 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 Web page created by an attacker. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites.

DETECTION

Internet Explorer versions 6 and 7 are vulnerable.

WORKAROUND

Since the vulnerability is triggered through JavaScript, disabling Active Scripting will prevent the exploitation of this vulnerability.

VENDOR RESPONSE

Microsoft Corp. has released patches which address this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown.

http://www.microsoft.com/technet/security/bulletin/MS11-018.mspx

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-0094 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

11/24/2010 Initial Vendor Notification
11/24/2010 Initial Vendor Reply
04/12/2011 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by anonymous.

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LEGAL NOTICES

Copyright © 2011 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.