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Multiple Vendor WebKit column-span RenderButton.m_inner Use-after-Free Vulnerability

07.25.12

BACKGROUND

WebKit is an open-source Web browser engine. It is currently used by Apple Inc.'s Safari browser and Google Inc.'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.

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

iDefense has confirmed the existence of this vulnerability in the following applications that use Webkit:

  • Safari 5.1.2 on Windows XP and OS X Lion
  • Safari 5.1.5 on Windows XP and OS X Lion
  • MobileSafari on an iPad 1, iOS 5.0.1
  • Chrome 16.0.912.75 m on Windows 7

WORKAROUND

Disabling JavaScript is an effective workaround for this vulnerability. However, disabling scripting can severely impact the usability of the browser.

VENDOR RESPONSE

Apple Inc. has released an update which addresses this issue. For more information, consult their advisory at the following URL: http://lists.apple.com/archives/security-announce/2012/Jul/msg00000.html

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-1520 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
04/04/2012 Initial Vendor Reply
07/25/2012 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by Jose A. Vazquez of spa-s3c.blogspot.com.

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LEGAL NOTICES

Copyright © 2012 Verisign, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customer service for permission.

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.