bugtraq - URL-Encoding Problem in Finjan SurfinGate

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Date: Tue, 14 Jun 2005 16:24:58 +0200
From: Daniel Schröter <d.schroeter@....de>
To: bugtraq@...urityfocus.com
Subject: URL-Encoding Problem in Finjan SurfinGate


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SUMMARY
- -------
The Finjan SurfinGate use web content filtering and internet access
management for protecting the network.

A vulnerability in the product allows you to bypass the access
management. You can download files which are normally blocked.


VERSIONS AFFECTED
- -----------------
Tested with SurfinGate Version 7.0SP2 and SP3 (and maybe others...)


DETAILS
- -------
A URL ASCII decode problem exists in the Finjan SurfinGate. If you use
ASCII encoding for a not allowed file the Finjan SufinGate can not block
it. Mostly it's enough to convert the dots to '%2e'. For example: you
can bypass a not allowed EXE-download or a double extension file like
file.jpg.exe.

If you block the content type of the file you can not bypass the Finjan
SurfinGate. But a hacker will not use a correct configured webserver for
infiltrate files in the company....

Finjan Software Ltd. has been notified for one year!


Proof of concept
- ----------------

(This example will not work if you block the content type in your
infrastructure, but there are some webservers out there with a wrong
content type for EXE-files.....)

Of course we don't take a normal exe-file. Let us use a screensaver.

If you block SCR-files the following will be blocked:
http://www.mustangworld.com/ourpics/sware/Mustangworld.scr

If you _just_ block the SCR-extension (and not the content type in you
infrastructure) your can bypass the Finjan SurfinGate with the following
link:
http://www.mustangworld.com/ourpics/sware/Mustangworld%2escr

Bye

	Daniel Schröter


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