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iDefense Security Advisory 02.24.09
http://labs.idefense.com/intelligence/vulnerabilities/
Feb 24, 2009

I. BACKGROUND

Adobe Flash Player is a very popular web browser plugin. It is available
for multiple web browsers and platforms, including Windows, Linux and
MacOS. Flash Player enables web browsers to display rich multimedia
content, such as online videos, and is often a requirement for popular
websites.

For more information, see the vendor's site found at the following link.

http://www.adobe.com/products/flashplayer

II. DESCRIPTION

Remote exploitation of a invalid object reference vulnerability in Adobe
Systems Inc.'s Flash Player could allow an attacker to execute arbitrary
code with the privileges of the current user.

During the processing of a Shockwave Flash file, a particular object can
be created, along with multiple references that point to the object. The
object can be destroyed and its associated references removed. However a
reference can incorrectly remain pointing to the object. The invalid
object resides in uninitialized memory, which the attacker may control
to gain arbitrary execution control.

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 Shockwave
Flash file created by an attacker. An attacker typically accomplishes
this via social engineering or injecting content into a compromised,
trusted site.

Utilizing various techniques, an attacker is able to re-allocate and
control the memory used by the destroyed object. This allows the
attacker to subvert execution when a virtual function is called via the
invalid reference.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in latest
version of Flash Player, version 9.0.124.0. Previous versions may also
be affected.

Exploitation of this vulnerability was tested on Windows XP SP3 and
Windows Vista SP1. iDefense believe that all platforms supported by
Flash Player are affected by this vulnerability, including Linux and
MacOS.

V. WORKAROUND

A Internet Explorer plugin is available to temporarily block and unblock
Flash content using a single click. Only trusted sites should be
unblocked when using this plugin. More information is available at
http://flash.melameth.com.

A Firefox plugin is available to temporarily block and unblock Flash
content using a single click. Only trusted sites should be unblocked
when using this plugin. More information is available at:
http://flashblock.mozdev.org.

VI. VENDOR RESPONSE

Adobe has released a patch which addresses this issue. For more
information, consult their advisory (APSB09-01) at the following URL:

http://www.adobe.com/support/flashplayer/

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2009-0520 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

08/25/2008  - Initial Contact
09/22/2008  - PoC Requested
11/05/2008  - PoC Sent
11/06/2008  - Clarification requested
12/05/2008  - Clarification Sent
12/07/2008  - Additional Clarification Sent
02/19/2009  - Draft bulletin received
02/24/2009  - Coordinated Public Disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Javier Vicente Vallejo,
http://www.vallejo.cc.

Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php

Free tools, research and upcoming events
http://labs.idefense.com/

X. LEGAL NOTICES

Copyright © 2009 iDefense, 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 customerservice@idefense.com 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.
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