iDefense Security Advisory 11.04.08
http://labs.idefense.com/intelligence/vulnerabilities/
Nov 04, 2008

I. BACKGROUND

Adobe Reader is a program for viewing Portable Document Format (PDF)
documents. Acrobat is the program used to create such documents. More
information is available at the following URLs.

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

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

II. DESCRIPTION

Remote exploitation of a heap corruption vulnerability in Adobe Systems
Inc.'s Acrobat Professional and Reader could allow an attacker to
execute arbitrary code with the privileges of the current user.

The vulnerable code is an AcroJS function available to scripting code
inside of a PDF document. This function is used for HTTP
authentication. By passing a long string to this function, it is
possible to corrupt heap memory in such a way that may lead to the
execution of arbitrary code.

III. ANALYSIS

Exploitation of this vulnerability would allow an attacker to execute
arbitrary code with the privileges of the current user. In order to
exploit this vulnerability, an attacker would have to convince the
target to open a maliciously constructed file, or to visit a website
with an embedded PDF. If the user has the Adobe Reader Browser plugin
enabled, the PDF file will render inside of the browser.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in Acrobat
Professional and Adobe Reader version 8.1.2. Previous versions may also
be affected.

V. WORKAROUND

Disabling JavaScript in Adobe Reader or Acrobat will limit exposure to
this vulnerability. When JavaScript is disabled, Adobe Reader will
prompt the user that some components of the document may not function,
and provide an opportunity to enable it.

VI. VENDOR RESPONSE

Adobe reports that the input validation issue in the Download Manager
used by Adobe Reader has been resolved and has released a patch which
addresses this issue. A patch is available from the vendor at:

http://www.adobe.com/support/security/bulletins/apsb08-19.html

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-4817 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

03/21/2008  Initial Vendor Notification
04/28/2008  Additional iDefense Data Provided to Vendor
06/26/2008  Additional Vendor Follow-up
11/04/2008  Coordinated Public Disclosure

IX. CREDIT

This vulnerability was reported to iDefense by an anonymous contributor.

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X. LEGAL NOTICES

Copyright © 2008 iDefense, Inc.

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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
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indirect, or consequential loss or damage arising from use of, or
reliance on, this information.