FREESCO public http server - Cross Site Scripting Vulnerabillity

["Rafel Ivgi, The-Insider" <theinsider () 012 net il>]

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Software:        FREESCO public http server - Running thttpd/2.05 09nov99
Vendor:           http://www.freesco.org
Versions:        2.05
Platforms:       Unix
Bug:                 Cross Site Scripting Vulnerabillity
Risk:                Low
Exploitation:   Remote with browser
Date:               22 Jan 2004
Author:            Rafel Ivgi, The-Insider
e-mail:             the_insider () mail com
web:                http://theinsider.deep-ice.com

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1) Introduction
2) Bug
3) The Code

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===============
1) Introduction
===============

thttpd is a free "Open Source" webserver that comes by default with unix
systems such as
FREEBSD and Linux. freesco edited thttpd and published their own version.

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======
2) Bug
======

The Vulnerabillity is Cross Site Scripting. If an attacker will request the
following
url from the server
http://<host>/cgi/example?test=<script>alert('xss')</script>
The vulnerabillity exists in the servers default cgi example.
XSS appears and the server allows an attacker to inject & execute scripts.

In the words of securityfocus.com :
~~~~~~~~~~~~~~~~~~~~~~~~~~

If all of these circumstances are met, an attacker may be able to exploit
this issue
via a malicious link containing arbitrary HTML and script code as part of
the hostname.
When the malicious link is clicked by an unsuspecting user, the
attacker-supplied HTML
and script code will be executed by their web client. This will occur
because the server
will echo back the malicious hostname supplied in the client's request,
without sufficiently
escaping HTML and script code.

Attacks of this nature may make it possible for attackers to manipulate web
content or to
steal cookie-based authentication credentials. It may be possible to take
arbitrary actions as the victim user.

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===========
3) The Code
===========

http://<host>/cgi/example?test=<script>alert('xss')</script>

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---
Rafel Ivgi, The-Insider
http://theinsider.deep-ice.com

"Things that are unlikeable, are NOT impossible."