Adobe Reader 6.0 Filename Handler Buffer Overflow Vulnerability

iDEFENSE Security Advisory 07.12.04:

I. BACKGROUND

Adobe Reader is a program used to display Portable Document Format (PDF)
documents.

II. DESCRIPTION

Exploitation of a buffer overflow vulnerability in Adobe Reader 6.0
could allow remote attackers to execute arbitrary code.

The problem specifically exists within a routine that is responsible for
splitting the filename path into multiple components. Due to a parsing
error involving NULL characters, an attacker can force Adobe Reader to
open a file containing an unhandled file extension. If an overly long
extension is supplied, a stack based overflow occurs.

III. ANALYSIS

Successful exploitation allows an attacker to execute arbitrary code
under the privileges of the local user. Remote exploitation is possible
by sending a specially crafted e-mail and attaching the malicious PDF
document.

IV. DETECTION

iDEFENSE has confirmed that Adobe Acrobat Reader version 6.0.1 is
vulnerable. It is suspected that other versions of Adobe Acrobat Reader
are vulnerable as well. Adobe Acrobat may also be vulnerable.

V. VENDOR RESPONSE

Coordinated public disclosure of this vulnerability did not occur.
According to Adobe, the vulnerability was patched on June 7, 2004 when
Adobe Reader 6.0.2 was released. A vendor security advisory was not
released but the following statement was included in a changelog
(http://www.adobe.com/support/techdocs/34222.htm) detailing the changes
included in the 6.0.2 update:

"Security update to further restrict malicious code execution."

Adobe's official response is below:

"Adobe Systems Incorporated recommends that users update to the latest
release of Adobe Acrobat and the free Adobe Reader, version 6.0.2.
Instructions and further information is available at:
http://www.adobe.com/support/techdocs/34222.htm."

VI. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-0632 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VII. DISCLOSURE TIMELINE

02/02/2004   Exploit discovered by iDEFENSE
03/11/2004   Initial vendor notification
03/11/2004   Initial vendor response
03/11/2004   iDEFENSE clients notified
06/07/2004   Vendor update released
07/12/2004   Public Disclosure

VIII. CREDIT

Greg MacManus (iDEFENSE Labs) is credited with this discovery.

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VI. LEGAL NOTICES

Copyright © 2004 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
email 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.