Adobe Acrobat Reader UnixAppOpenFilePerform() Buffer Overflow
Vulnerability
iDEFENSE Security Advisory 07.05.05
www.idefense.com/application/poi/display?id=279&type=vulnerabilities
July 05, 2005
I. 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
II. DESCRIPTION
Remote exploitation of a buffer overflow in Adobe Acrobat Reader for
Unix could allow an attacker to execute arbitrary code.
The vulnerability specifically exists in the function
UnixAppOpenFilePerform(). This routine is called by Acrobat Reader while
opening a document containing a /Filespec tag. Within this routine,
sprintf is used to copy user-supplied data into a fixed-sized stack
buffer. This leads to a stack based overflow and the execution of
arbitrary code. The following demonstrates what the overflow looks like
in a debugger:
#0 0x41414141 in ?? ()
(gdb) i r ebx
ebx 0xbfffef54 -1073746092
(gdb) x/x 0xbfffef54
0xbfffef54: 0x40404040
(gdb)
As shown, EIP is easily controllable; ebx also points to the 4 bytes
before the EIP overwrite in a controlled buffer. This allows remote
exploitation without having to know stack addresses, as an attacker can
craft an exploit to return to a jmp ebx or call ebx instruction.
III. ANALYSIS
Successful exploitation allows an attacker to execute arbitrary code
under the privileges of the local user. Remote exploitation is possible
via e-mail attachment or link to the maliciously crafted PDF document.
The impact of this vulnerability is lessened by the fact that two error
messages appear before exploitation is successful; however, closing
these windows does not prevent exploitation from occurring.
IV. DETECTION
iDEFENSE has confirmed the existence of this vulnerability in Adobe
Acrobat Reader version 5.0.9 for Unix and Adobe Acrobat Reader version
5.0.10 for Unix. Adobe Acrobat for Windows is not affected. Adobe
Acrobat 7.0 for Unix is not affected.
V. 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 or unsolicited e-mail.
Users should consider using an unaffected version of Adobe Acrobat, such
as Acrobat 7.0
VI. VENDOR RESPONSE
Adobe has addressed this issue in the following security advisory:
http://www.adobe.com/support/techdocs/329083.html
Adobe is recommending the following steps for remediation:
-- If you use Adobe Reader 5.0.9 or 5.0.10 on Linux or Solaris,
download Adobe Reader 7.0 at
www.adobe.com/products/acrobat/readstep2.html.
-- If you use Adobe Reader 5.0.9 or 5.0.10 on IBM-AIX or HP-UX,
download Adobe Reader 5.0.11 at
www.adobe.com/products/acrobat/readstep2.html.
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-1625 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
05/12/2005 Initial vendor notification
05/12/2005 Initial vendor response
07/05/2005 Public disclosure
IX. CREDIT
iDEFENSE Labs is credited with this discovery.
Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp
Free tools, research and upcoming events
http://labs.idefense.com
X. LEGAL NOTICES
Copyright (c) 2005 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.
_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/
