iDefense Security Advisory 07.20.11
http://labs.idefense.com/intelligence/vulnerabilities/
Jul 20, 2011

I. 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/

II. DESCRIPTION

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

Scalable Vector Graphics (SVG) is an XML based file format used to
describe two dimensional vector graphics. It defines both a markup
language, and a JavaScript interface.

When parsing a series of SVG tags, and then manipulating them via
JavaScript, Safari fails to handle exceptional conditions. It is
possible to trigger a use after free vulnerability by manipulating the
animVal property of various SVG tags. This leaves a C++ object pointer
in an inconsistent state, which can lead to 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 webpage
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.

IV. DETECTION

Safari versions prior to 5.1 and 5.0.6 are vulnerable.

V. WORKAROUND

Disabling JavaScript is an effective workaround for this vulnerability.

VI. VENDOR RESPONSE

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

http://support.apple.com/kb/HT4808

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2011-0240 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

12/01/2010  Initial Vendor Notification
12/01/2010  Initial Vendor Reply
07/20/2011  Coordinated Public Disclosure

IX. CREDIT

This vulnerability was reported to iDefense by wushi of team509.

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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.