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Network Security VulnWatch
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[VulnWatch] Microsoft Windows image rendering DoS vuln

Subject: [VulnWatch] Microsoft Windows image rendering DoS vuln
Date: Mon, 11 Apr 2005 16:59:37 -0400
Alpha-Pi-Omicron Pi-Alpha-Nu-Tau-Omicron-C?
Kappa-Alpha-Kappa-Omicron-Delta-Alpha-Iota-Mu-Omicron-Nu-Omicron-C?
__ ___ __ _____ _ _ ___ _ _
/ / /___\/ // _ / /\ /(_) __ _| |__ / __\___ _ _ _ __ ___(_) |
/ / // // / \// / / /_/ / |/ _` | '_ \ / / / _ \| | | | '_ \ / __| | |
/ /___/ \_// /___/ //\ / __ /| | (_| | | | | / /__| (_) | |_| | | | | (__| | |
\____/\___/\____/____/ \/ /_/ |_|\__, |_| |_| \____/\___/ \__,_|_| |_|\___|_|_|
|___/


Overview

There exists a vulnerabilility in the way Microsoft Windows handles the rendering
of images. By resizing an image with html properties to an extremely large size an
attacker may perform a very quick and effective denial of service attack upon a
victim.



I. Description and PoC

Only clients running Internet Explorer, Firefox, or Avant in Windows 2k or XP have
been confirmed to be vulnerable. Opera does it's own image rendering and is not
ulnerable to this method of attack. The status of Longhorn is not known. Other
operating systems, including Mac OS X and Linux are not vulnerable.


You may point your browser to this URL to see a live demonstration of this attack:

http://www.livejournal.com/users/deeplolz

This may cause an instant reboot or bluescreen detailing a problem with your video
drivers. Other possibilities include an extended period of poor performance until
next reboot, a short to medium period of nonfunctionality or a crash of the
browser.



II. Impact

Because this attack can be performed anywhere an img src is allowed, there are
many forums including blogs, messageboards, and others which are vulnerable. It
is hopeful that Microsoft will release a patch for this attack as soon as
possible.



III. Solution

Until a patch is released you are advised to use the Opera web browser. It might
also be possible to write a script for the Firefox "GreaseMonkey" extension which
performs a workaround for this attack. Such as setting height and width of images
to 5000 pixels if they are currently set to render at over 5000.



Very special shouts: Girlvinyl, Hepkitten, Confkids, and Frienditto (Come back!!!
We need you badly, FD!)


Shouts:
LJD, LJ-Zeera, Encyclopedia Dramatica, Lulz News Network, Project Mayhem, Amalea,
Wednesday Night Karate Explosion, The Gundanium Alloys Manufacturers Association,
Richmond Flash Mob Society, RVA_BS, RVA_FYAD, Brad Fitzpatrick, Mena Trott, SALJ,
The International Department of Internet Security, #telconinjas, undernet #drugs,
The Kadaitcha Dancers, psychotic vegans, Warren Ellis, and pro-ana preteen girls.


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