Public Vulnerability Reports

Microsoft Internet Explorer Use-after-Free Vulnerability

12.06.12

BACKGROUND

Internet Explorer is Microsoft's web browser for the Windows platform.

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 center element is dynamically modified via JavaScript code. When this occurs, an HTML object is freed, while a reference to it remains. This reference is later reused, potentially leading to stale data being accessed. The result of this could allow an attacker to execute 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 that an attacker created. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites. After a user visits the malicious Web page, no further user interaction is needed.

DETECTION

Internet Explorer versions 6, 7, and 8 are vulnerable.

WORKAROUND

Since the vulnerability is triggered through JavaScript, disabling ActiveScript code on untrusted sites will prevent the exploitation of this vulnerability.

VENDOR RESPONSE

Microsoft Corp. has released patches which addresses this issue. For more information, consult their advisory at the following URL:

http://technet.microsoft.com/en-us/security/bulletin/ms12-037

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-1523 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

03/07/2012 Initial Vendor Notification
03/07/2012 Initial Vendor Reply
06/12/2012 Coordinated Public Disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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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.