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Adobe Acrobat Reader 5.0.9 mailListIsPdf() Buffer Overflow Vulnerability

12.14.04

BACKGROUND

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

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

DESCRIPTION

Remote exploitation of a buffer overflow in version 5.09 of Adobe
Acrobat Reader for Unix could allow for execution of arbitrary code.

The vulnerability specifically exists in a the function mailListIsPdf().
This function checks if the input file is an email message containing
a PDF. It unsafely copies user supplied data using strcat into a fixed
sized buffer.

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 either the
maliciously crafted PDF document or a link to it.

DETECTION

iDEFENSE has confirmed the existence of this vulnerability in Adobe
Acrobat Reader version 5.0.9 for Unix. Previous versions of Adobe
Acrobat Reader 5 for Unix are suspected also to be vulnerable.

WORKAROUND

User awareness is the best defense against this class of attack.
Users should be aware of the existence of such attacks and proceed with
caution when following links from suspicious and/or unsolicited e-mail.

Additionally, you may wish to apply the following unofficial patch from
iDEFENSE Labs to the acroread shell script. The acroread shell script
calls the appropriate binary for the platform. The patch adds a check
that ensures that files passed as arguments to acroread are in fact PDF
documents. This patch will not protect against files opened from within
the Acrobat Reader GUI.

The bin/ directory of the application contains an 'acroread' shell
script while the Reader/ directory contains a binary with the same name.
The command 'file acroread', when executed in the same directory as the
shell script, should return the line:

acroread: a /bin/sh script text executable

This result indicates the existence of the appropriate file that the
patch below can be applied to.

acroread.patch:

--- acroread.orig 2004-10-13 17:25:57.000000000 -0400
+++ acroread 2004-10-13 17:55:43.000000000 -0400
@@ -309,6 +309,16 @@
 fi
 
 if [ -f "$ACRO_EXEC_CMD" ] ; then
+  for CHECK in ${1+"$@"};
+  do
+   [ -f "$CHECK" ] && {
+    file "$CHECK" | grep "PDF document" ||
+    {
+     echo "$CHECK" exists, but is not a PDF document.
+     exit 1;
+    }
+   }
+   done
   exec "$ACRO_EXEC_CMD" ${1+"$@"}
 else
   echo "ERROR: Cannot find $ACRO_EXEC_CMD"

This is not an official patch, and may not operate on your system. This
patch was supplied to mitigate exposure until a vendor supplied patch
became available. The vendor supplied patch, which is now available,
should be applied instead of this patch when possible.

VENDOR RESPONSE

This vulnerability is fixed in Adobe Acrobat Reader 5.0.10 for Unix.
Further details of the vulnerability are available in the following
knowledgebase article:

   http://www.adobe.com/support/techdocs/331153.html

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-1152 to this issue. This is a candidate for inclusion
in the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

DISCLOSURE TIMELINE

10/14/2004   Initial vendor notification
10/15/2004   Initial vendor response
12/14/2004   Coordinated public disclosure

CREDIT

This vulnerability was discovered by Greg MacManus, iDEFENSE Labs.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

LEGAL NOTICES

Copyright © 2004 Verisign, 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.