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

I. BACKGROUND

MathML is an XML-based markup language used to describe mathematical
operations. It can be embedded inside of HTML and is supported by the
WebKit engine.

II. 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. <BR><BR>
The vulnerability occurs during the processing of MathML markup tags.
Specifically, it is possible to trigger a use-after-free vulnerability
when Safari fails to properly release an object. The object's memory is
freed; however, a reference to the object remains. When the reference is
later used to access the object, this now invalid memory is treated as a
valid object and the object's vtable is used to make an indirect
function call. This may result in 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 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.

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-2011-1449 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

12/15/2010  Initial Vendor Notification
12/15/2010  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,
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