[VulnWatch] iDEFENSE Security Advisory 07.05.05: Adobe Acrobat Reader UnixAppOpenFilePerform() Buffer Overflow Vulnerability

From: iDEFENSE Labs (labs-no-reply_at_idefense.com)
Date: 07/05/05

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    Date: Tue, 5 Jul 2005 16:25:08 -0400
    To: <bugtraq@securityfocus.com>, <vulnwatch@vulnwatch.org>, <full-disclosure@lists.grok.org.uk>
    
    

    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.


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