iDefense Security Advisory 04.12.11: Microsoft Internet Explorer Use-After-Free Memory Corruption Vulnerability

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iDefense Security Advisory 04.12.11
http://labs.idefense.com/intelligence/vulnerabilities/
Apr 12, 2011

I. 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: <BR> <BR>
http://www.microsoft.com/windows/internet-explorer/default.aspx

II. 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. <BR> <BR> 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.

III. 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.

IV. DETECTION

Internet Explorer versions 6 and 7 are vulnerable.

V. WORKAROUND

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

VI. 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

VII. 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.

VIII. DISCLOSURE TIMELINE

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

IX. CREDIT

This vulnerability was reported to iDefense by anonymous.

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X. LEGAL NOTICES

Copyright © 2011 Verisign

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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.