Public Vulnerability Reports

Adobe Flash Player Invalid Object Reference Vulnerability



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.


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.


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.


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

Additionally, Adobe Systems Inc. confirmed the existence of this vulnerability in all versions of Flash Player 9 prior to 9.0.159 and in Flash Player and earlier.

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.


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

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:


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


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 (, which standardizes names for security problems.


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


This vulnerability was reported to iDefense by Javier Vicente Vallejo,

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Copyright © 2009 Verisign, Inc.

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