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Multiple Vendor WebKit Use After Free Vulnerability

30.04.12

BACKGROUND

WebKit is an open source web browser engine. It is currently used by Apple Inc.'s Safari browser, as well as by Google's Chrome browser. For more information, see the vendor's site at the following link.

http://webkit.org/

DESCRIPTION

Remote exploitation of a use-after-free vulnerability in WebKit, as included with multiple vendors' browsers, could allow an attacker to execute arbitrary code with the privileges of the current user.

This vulnerability occurs when manipulating the DOM tree via asynchronous JavaScript Event Handlers. Specifically, it is possible for the same DOM node to be attached to two different rendering contexts, which can lead to a use-after-free vulnerability when one of the rendering objects is destroyed. The stale reference remains attached to the second rendering object, which triggers a use-after-free vulnerability when it is later destroyed.

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

Google Chrome versions prior to 18.0.1025.168 are vulnerable.

WORKAROUND

iDefense is currently unaware of any workaround for this issue.

VENDOR RESPONSE

Google has released an updated version which addresses this issue. For more information, consult their advisory at the following URLs:

http://googlechromereleases.blogspot.com/2012/04/stable-channel-update_30.html

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-1521 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

04/04/2012 Initial Vendor Notification
04/05/2012 Initial Vendor Reply
04/30/2012 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by wushi of team509.

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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.