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Digital Armaments Security Advisory 12.20.2005: WEBsweeper/MIMEsweeper Executable File Content Check bypass Vulnerability



WEBsweeper/MIMEsweeper Executable File Content Check bypass Vulnerability 


Digital Armaments advisory is 12.15.2005
http://www.digitalarmaments.com/2005161283546323.html

I. Background

WEBsweeeper/MIMEsweeper is a commercial software that brings policy-based 
content security to the HTTP gateway. For many information or detail about the 
software you can refer to the vendor's homepage:

http://www.mailsweeper.com/

II. Problem Description

An attacker could trick a user to click on a mail link/attachment to download 
and run a malicious code (any malicious application in a .exe file). The ".exe" 
files should be filtered according to the security policies, but an attacker 
can trick to fail this test if the data sent to the webserver does not include 
the ".exe" extension. This problem persist on all platform where the data sent 
to a webserver (GET or POST) is fetched via a server side language (asp, php, 
etc..) that doesn't explicitly contain those regular expression. An example is:

http://yourattack.server/asp?cmd=data&maliciouscodewithnumber&number=123

III. Detection

This problem has been detected on latest version of WEBsweeper and MIMEsweeper 
actually avaiable and on prior version. It persist on all platforms.

IV. Impact analisys

Successful exploitation allow an attacker to easily trick a user to execute 
malicious code on his system. This attack bypass the protection offered by 
those content filter application. No exploit code is required. This attack can 
also be use in a massive way versus clients systems.

V. Solution

The vendor has given no response.
First notification 12.15.2005.
Second notification 12.19.2005.

VI. Credit

Oliver Muenchow - o.muenchow@xxxxxxxxxxxxx is credited with this discovery.

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VII. Legal Notices

Copyright © 2005 Digital Armaments LLC. 

Redistribution of this alert electronically is allowed. It should not be edited 
in any way. Reprint the whole is allowed, partial reprint is not permitted. For 
any other request please email customerservice@xxxxxxxxxxxxxxxxxxxx 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.