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Microsoft Internet Explorer Time2 Element Behavior Use-After-Free Vulnerability

06.14.11

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/ie/

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 the HTML content within a sequence time container is modified and a certain attribute has been set on the container. An object is created and this object's memory is later freed; however, a reference to the object remains within a another object. When the reference is later used to access the other object, this now-invalid memory is treated as valid. The corrupt object's vtable 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. After the user visits the malicious Web page, no further user interaction is needed.

DETECTION

The following Microsoft products are vulnerable:

  • Internet Explorer 7
  • Internet Explorer 8
  • Internet Explorer 9

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/MS11-050.mspx

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-1255 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

01/26/2011 Initial Vendor Notification
01/26/2011 Initial Vendor Reply
06/14/2011 Coordinated Public Disclosure

CREDIT

The discoverer of this vulnerability wishes to remain 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.