bugtraq - Re: Bypassing of web filters by using ASCII

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Date: Sun, 25 Jun 2006 17:42:07 +0200
From: David Huecking <d.huecking@....net>
To: bugtraq@...urityfocus.com
Subject: Re: Bypassing of web filters by using ASCII


Am Mittwoch, 21. Juni 2006 15:11 schrieb k.huwig@...-ag.de:
[...]
> Product               : Microsoft InternetExplorer 6
[...]


> Of the tested browsers Firefox 1.5, Opera 8.5 and InternetExplorer 6,
> only the InternetExplorer does this correctly, the others evaluate the
> bit and display the characters as if they were from the character set
> ISO-8859-1. Although the behaviour of the InternetExplorer is the
> correct one, this creates a security risk: the author of a web page can
[...]

>       http://www.iku-ag.de/ASCII
>
> you can find a test page that displays a secret message. IE6 displays
> the text correctly, Firefox 1.5 and Opera 8.5 display glibberish text.
> This page only shows that IE6 displays ASCII-text correctly and does not
> contain any content that a filter should sort out.
[...]

> There is no workaround know to us.
> --
> Kurt Huwig iKu Systemhaus AG http://www.iku-ag.de/ Vorstand Am Römerkastell
> 4 Telefon 0681/96751-0 66121 Saarbrücken Telefax 0681/96751-66 GnuPG
> 1024D/99DD9468 64B1 0C5B 82BC E16E 8940 EB6D 4C32 F908 99DD 9468

Running MS Internet Explorer 6SP1 (German) with wine under Linux does also 
display the text like Firefox 1.5 and Konqueror.
http://www.iku-ag.de/ascii.cgi.htm
is also displayed like in the "native" programs (garbage).


...just my 2 cents,
David.
-- 
Eat, sleep and go running, ;-)
David Huecking.

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