Home page logo
/

bugtraq logo Bugtraq mailing list archives

Re: iDEFENSE Security Advisory 12.21.04: libtiff STRIPOFFSETS Integer Overflow Vulnerability
From: "Dmitry V. Levin" <ldv () altlinux org>
Date: Wed, 22 Dec 2004 14:45:45 +0300

Hi,

On Tue, Dec 21, 2004 at 05:09:30PM -0500, customer service mailbox wrote:
libtiff STRIPOFFSETS Integer Overflow Vulnerability

iDEFENSE Security Advisory 12.21.04
www.idefense.com/application/poi/display?id=173&type=vulnerabilities
December 21, 2004

I. BACKGROUND

libtiff provides support for the Tag Image File Format (TIFF), a widely 
used format for storing image data.

More information is available at the following site: 
http://www.remotesensing.org/libtiff/

II. DESCRIPTION

Remote exploitation of an integer overflow in libtiff may allow for the 
execution of arbitrary code.

The overflow occurs in the parsing of TIFF files set with the 
STRIPOFFSETS flag in libtiff/tif_dirread.c. In the TIFFFetchStripThing()

function, the number of strips (nstrips) is used directly in a 
CheckMalloc() routine without sanity checking. The call ultimately boils

down to:

malloc(user_supplied_int*size(int32));

When supplied 0x40000000 as the user supplied integer, malloc is called 
with a length argument of 0. This has the effect of returning the 
smallest possible malloc chunk. A user controlled buffer is subsequently

copied to that small heap buffer, causing a heap overflow.

When exploited, it is possible to overwrite heap structures and seize 
control of execution.

III. ANALYSIS

An attacker can exploit the above-described vulnerability to execute 
arbitrary code under the permissions of the target user. Successful 
exploitation requires that the attacker convince the end user to open 
the malicious TIFF file using an application linked with a vulnerable 
version of libtiff. Exploitation of this vulnerability against a remote 
target is difficult because of the precision required in the attack.

IV. DETECTION

iDEFENSE has confirmed this vulnerability in libtiff 3.6.1. Changes were

introduced in libtiff 3.7.0 that had the effect of fixing this 
vulnerability.

The following vendors provide susceptible libtiff packages within their 
respective operating system distributions: 
      
      - Gentoo Linux 
      - Fedora Linux 
      - RedHat Linux 
      - SuSE Linux 
      - Debian Linux 

V. WORKAROUND

Only open TIFF files from trusted users.

VI. VENDOR RESPONSE

This issue is addressed in libtiff 3.7.0 and 3.7.1.

VII. CVE INFORMATION

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

I believe this issue is subset of CAN-2004-0886 which was fixed in the
middle of October.


-- 
ldv

Attachment: _bin
Description:


  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]