iDEFENSE Security Advisory 12.21.04: Multiple Vendor xpdf PDF Viewer Buffer Overflow Vulnerability

From: customer service mailbox (customerservice_at_idefense.com)
Date: 12/21/04

  • Next message: customer service mailbox: "iDEFENSE Security Advisory 12.21.04: Multiple Vendor Xine version 0.99.2 PNM Handler Negative Read Length Heap Overflow Vulnerability" 
    Date: Tue, 21 Dec 2004 17:09:09 -0500
To: <bugtraq@securityfocus.com>, <vulnwatch@vulnwatch.org>

    Multiple Vendor xpdf PDF Viewer Buffer Overflow Vulnerability

    iDEFENSE Security Advisory 12.21.04
    www.idefense.com/application/poi/display?id=172&type=vulnerabilities
    December 21, 2004

    I. BACKGROUND

    Xpdf is an open-source viewer for Portable Document Format (PDF) files.

    II. DESCRIPTION

    Remote exploitation of a buffer overflow vulnerability in the xpdf PDF
    viewer, as included in multiple Linux distributions, could allow
    attackers to execute arbitrary code as the user viewing a PDF file. The
    offending code can be found in the Gfx::doImage() function in the source

    file xpdf/Gfx.cc.

    void Gfx::doImage(Object *ref, Stream *str, GBool inlineImg) {
      Dict *dict;
      int width, height;
      int bits;
      GBool mask;
      GBool invert;
      GfxColorSpace *colorSpace;
      GfxImageColorMap *colorMap;
      Object maskObj;
      GBool haveMask;
      int maskColors[2*gfxColorMaxComps];
      Object obj1, obj2;
      int i;

      ...
        // get the mask
        haveMask = gFalse;
        dict->lookup("Mask", &maskObj);
            if (maskObj.isArray()) {
              for (i = 0; i < maskObj.arrayGetLength(); ++i) {
            maskObj.arrayGet(i, &obj1);
    [!] maskColors[i] = obj1.getInt();
                obj1.free();
              }
              haveMask = gTrue;
            }
      ...
    }

    Due to the fact that the loop boundaries are not less than the storage
    area, the maskColors array is eventually filled up. After that, local
    variables and other stack memory is overwritten. This ultimately leads
    to control of program flow and arbitrary code execution.

    III. ANALYSIS

    The severity of this issue is mitigated by the fact that several of the
    local overwritten variables in doImage() are referenced prior to EIP
    being restored; therefore, before the attack gains control of the target

    process. However, an attacker with knowledge of the remote operating
    system can construct and validate a malicious payload before attempting
    exploitation, thus increasing the chances of success. An attacker must
    convince a target user to open the malicious file to exploit this
    vulnerability.

    IV. DETECTION

    iDEFENSE has confirmed the existence of this vulnerability in version
    3.00 of xpdf. It is suspected previous versions are also vulnerable.

    The follwing vendors included vulnerable xpdf packages:

            Novell SUSE
            Red Hat, Inc.
            Fedora Project
            Debian Project
            Gentoo Foundation
            FreeBSD Project (ports)
            OpenBSD

    V. WORKAROUND

    Only open PDF files from trusted individuals.

    VI. VENDOR RESPONSE

    A patch to address this vulnerability is available from:

        ftp://ftp.foolabs.com/pub/xpdf/xpdf-3.00pl2.patch

    Updated binaries (version 3.00pl2) are available from:

        http://www.foolabs.com/xpdf/download.html

    VII. CVE INFORMATION

    The Common Vulnerabilities and Exposures (CVE) project has assigned the
    names CAN-2004-1125 to these issues. This is a candidate for inclusion
    in the CVE list (http://cve.mitre.org), which standardizes names for
    security problems.

    VIII. DISCLOSURE TIMELINE

    11/23/2004 Initial vendor notification
    11/29/2004 Initial vendor response
    12/21/2004 Coordinated public disclosure

    IX. CREDIT

    The discoverer of this vulnerability wishes to remain anonymous.

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

    X. LEGAL NOTICES

    Copyright (c) 2004 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.

  • Next message: customer service mailbox: "iDEFENSE Security Advisory 12.21.04: Multiple Vendor Xine version 0.99.2 PNM Handler Negative Read Length Heap Overflow Vulnerability"

    Relevant Pages