iDefense Security Advisory 02.08.08: Adobe Reader Security Provider Unsafe Libary Path Vulnerability

iDefense Security Advisory 02.08.08
http://labs.idefense.com/intelligence/vulnerabilities/
Feb 08, 2008

I. BACKGROUND

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

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

II. DESCRIPTION

Remote exploitation of an unsafe library path vulnerability in Adobe
Systems Inc.'s Adobe Reader may allow attackers to execute arbitrary
code as the current user.

This vulnerability is due to Adobe Reader using a path for "Security
Provider" libraries that contains the directory the application was
started in. Security Provider libraries provide encryption and
signature verification routines to applications. If the current
directory contains a file with the same name as a Security Provider
library, the file will be loaded into the application, potentially
allowing code execution.

III. ANALYSIS

Exploitation allows an attacker to execute arbitrary code as the user
that started the application. To exploit this vulnerability, the
attacker must convince the targeted user to open a PDF from a directory
under their control. This directory may be local or network based on
either an SMB or WebDAV server. If Adobe Reader has already been
started, the library will not be loaded.

IV. DETECTION

iDefense has confirmed this vulnerability exists in Adobe Reader 8.1
installed on Windows XP and Windows Vista. Previous versions, as well
as those for other platforms, may also be affected.

V. WORKAROUND

Copying the original library from "%WINDIR%\System32" to the same
directory as the AcroRd32.exe binary will make the application find the
correct library before a malicious one is found.

The actual filenames which can be used to exploit this vulnerability
depend on the operating system and version. To determine which
filenames affect your system, consult the following registry key.

HKLM\System\CurrentControlSet\Control\SecurityProviders\SecurityProviders

This is only a temporary workaround; future software updates will not
update these copies. As such, the copies should be removed once this
vulnerability has been patched.

VI. VENDOR RESPONSE

Adobe has released version 8.1.2 of Adobe Reader that addresses this
vulnerability. Although there is currently no update for version 7.0.9,
Adobe reports it does plan to release one at a later date. For more
information, visit the vendor's advisory at the following URL.

http://www.adobe.com/support/security/advisories/apsa08-01.html

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-5666 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

09/25/2007 Initial vendor notification
09/25/2007 Initial vendor response
10/26/2007 Request for status
10/26/2007 Status - Est. early January
01/04/2008 Request for status
01/04/2008 Status - Scheduled early February
01/28/2008 Adobe plans patch for 8, but not 7
01/30/2008 Concerns about the plan e-mailed to Adobe
01/31/2008 Telephone call to clarify concerns
02/06/2008 Adobe releases 8.1.2
02/07/2008 Adobe publishes APSA08-01
02/08/2008 Public disclosure

IX. CREDIT

This vulnerability was discovered by Greg MacManus of VeriSign iDefense
Labs.

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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
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.