Bug 129642 (CVE-2005-3186)

Hi,
we reveive this message via vendor-sec.

CRD: 3rd Nov. 2005
CAN-2005-3186.

To: vendor-sec@lst.de
Cc: mclasen@redhat.com, vendor-disclosure@idefense.com
From: Josh Bressers <bressers@redhat.com>
Subject: [vendor-sec] iDEFENSE gdk-pixbuf/gtk+ XPM buffer overflow
Errors-To: vendor-sec-admin@lst.de
Date: Wed, 19 Oct 2005 13:06:36 -0500

iDEFENSE recently contacted the gdk-pixbuf/gtk+ maintainers with the
following advisory.  The demo exploit and patch were written by one of our
developers, Matthias Clasen.  He asked me to forward this on to vendor-sec.

The current embargoed date is Nov 3.  This issue has been assigned the CVE
id CAN-2005-3186.

--
    JB


Content-Description: xpm-advisory.txt
Multiple Vendor GTK+ gdk-pixbuf XPM Loader Heap Overflow Vulnerability

iDEFENSE Security Advisory XX.XX.05
http://www.idefense.com/application/poi/display?type=vulnerabilities
MMM DD, 2005

I. BACKGROUND

GTK+ is a multi-platform toolkit for creating graphical user interfaces.
Offering a complete set of widgets, GTK+ is suitable for projects
ranging from small one-off projects to complete application suites.

II. DESCRIPTION

Remote exploitation of heap overflow vulnerability in various vendors'
implementations of the GTK+ gdk-pixbuf XPM image rendering library could
allow for arbitrary code execution. iDEFENSE is currently unaware of
exploits for this vulnerability other than those maintainted by iDEFENSE
Labs, however exploitation is trivial. Vendor patches for this iDEFENSE
exclusive report are currently unavailable. A workaround has been
provided.

The vulnerability specifically exists due to an integer overflow while
processing XPM files. The following code snippet illustrates the
vulnerability:

if (n_col <= 0 || n_col >= G_MAXINT / (cpp + 1)) {
                g_set_error (error,
                             GDK_PIXBUF_ERROR,
                             GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
                             _("XPM file has invalid number of colors"));
        return NULL;
    }
[...]
colors = (XPMColor *) g_try_malloc ((sizeof (XPMColor) * n_col));
[...]


The validity check of n_col is enough to prevent an integer overflow in
the first g_try_malloc, however there is not a proper check for the
second g_try_malloc, which allows an undersized heap buffer to be
allocated, then overflowed while using n_col as an upper bounds in a
copying loop. This can be used to execute arbitrary code via traditional
heap overflow 4 byte write methods or by overwriting adjacent areas of
the heap with important values such as function pointers.

III. ANALYSIS

Exploitation could allow for arbitrary code execution in the context of
the user running the affected application. As this library is used in a
variety of applications, this vulnerability could be exploited either
remotely, via a networked application or locally.

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in gtk+ 2.4.0
compiled from source. It is suspected that previous versions are also
affected by this vulnerability. The following vendors include
susceptible GTK+ and GdkPixBuf packages within their respective
operating system distributions:

        The Debian Project: Debian GNU/Linux 3.0 and 3.1 (all architectures)
        Mandriva (formerly Mandrakesoft): Mandriva Linux (formerly
Mandrakelinux) 10.0 and 10.1, Corporate Server 3.0
        Novell Inc. SuSE Linux 8.2, 9.0, 9.1 and 9.2
        Red Hat Inc.: Linux 9.0 and 7.3, Fedora Core 1, 2,3 and 4, Desktop v.3
and v.4, Enterprise Linux AS/ES/WS v.2.1, v.3 and v.4 and Advanced
+Workstation 2.1 for the Itanium Processor

V. WORKAROUND

Do not open untrusted media files.

VI. VENDOR RESPONSE

[Quoted vendor response if available. Otherwise include vendor fix
details.]

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-XXXX to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

[OR]

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.

VIII. DISCLOSURE TIMELINE

10/12/2005  Initial vendor notification
XX/XX/2005  Initial vendor response
XX/XX/2005  Coordinated public disclosure

IX. CREDIT

infamous41md is credited with the discovery of this vulnerability.

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 ￜ 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.
Content-Description: xpm-overflow.patch
Index: io-xpm.c
===================================================================
RCS file: /cvs/gnome/gtk+/gdk-pixbuf/io-xpm.c,v
retrieving revision 1.49
diff -u -p -r1.49 io-xpm.c
--- io-xpm.c    8 Mar 2005 03:59:45 -0000       1.49
+++ io-xpm.c    14 Oct 2005 04:10:30 -0000
@@ -500,7 +500,9 @@ pixbuf_create_from_xpm (const gchar * (*
                              _("XPM has invalid number of chars per pixel"));
                return NULL;
        }
-       if (n_col <= 0 || n_col >= G_MAXINT / (cpp + 1)) {
+       if (n_col <= 0 ||
+           n_col >= G_MAXINT / (cpp + 1) ||
+           n_col >= G_MAXINT / sizeof (XPMColor)) {
                 g_set_error (error,
                              GDK_PIXBUF_ERROR,
                              GDK_PIXBUF_ERROR_CORRUPT_IMAGE,



----- End forwarded message -----