Multiple Vendor xzgv PRF Parsing Integer Overflow Vulnerability
iDEFENSE Security Advisory 12.13.04
http://www.idefense.com/application/poi/display?id=160&type=vulnerabilit
ies
December 13, 2004
I. BACKGROUND
xzgv is a picture viewer for X, with a thumbnail-based file selector. It
uses GTK+ and Imlib 1.x. Most file formats are supported, and the
thumbnails used are compatible with xv, zgv and the Gimp.
II. DESCRIPTION
Remote exploitation of an integer overflow vulnerability in various
vendors' implementations of the read_prf_file method in the xzgv program
could allow for arbitrary code execution. The vulnerability specifically
exists due to an integer overflow while allocating memory for an image
file. The vulnerable code is as follows:
xzgv-0.8/src/readprf.c:
if((*theimageptr=malloc(width*height*3))==NULL)
[...]
The values width and height are integers that are ultimately supplied by
the image file. With certain values for height and width set in an image
file, not enough memory is allocated due to an integer overflow. The
underallocated memory is later written to, causing heap corruption and
possible arbitrary code execution with the privileges of the user
viewing the image file.
III. ANALYSIS
Exploitation allows attackers to gain the privileges of the user viewing
the image file. If a user can be convinced to view a malicious file,
this vulnerability can be exploited remotely.
IV. DETECTION
The following vendors have confirmed the availability of susceptible
xzgv packages within their respective operating system distributions:
SuSE
Debian
Gentoo
FreeBSD
V. WORKAROUND
Only accept image files from trusted sources. Use a different image
viewer program to view untrusted images.
VI. VENDOR RESPONSE
The vulnerability has been addressed in the following patch:
http://rus.members.beeb.net/xzgv-0.8-integer-overflow-fix.diff
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-0994 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
11/05/2004 Initial vendor notification
12/10/2004 Secondary vendor notification
12/10/2004 Initial vendor response
12/13/2004 Coordinated public disclosure
IX. CREDIT
Infamous41md is credited with this discovery.
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
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part of this alert in any other medium other than electronically, please
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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.
