BugTraq
Bypassing of web filters by using ASCII Jun 21 2006 01:11PM
k huwig iku-ag de (4 replies)
Re: Bypassing of web filters by using ASCII Jun 22 2006 10:08PM
Amit Klein (AKsecurity) (aksecurity hotpop com)
Re: Bypassing of web filters by using ASCII Jun 22 2006 02:57PM
Hubert Seiwert (hubert westpoint ltd uk)
Re: Bypassing of web filters by using ASCII Jun 21 2006 11:57PM
RSnake (rsnake shocking com) (2 replies)
Re: Bypassing of web filters by using ASCII Jun 25 2006 03:42PM
David Huecking (d huecking gmx net)
Re: Bypassing of web filters by using ASCII Jun 22 2006 12:34AM
Kurt Huwig (k huwig iku-ag de)
Re: Bypassing of web filters by using ASCII Jun 21 2006 08:15PM
Fixer (fixer gci net) (1 replies)
Re: Bypassing of web filters by using ASCII Jun 21 2006 10:24PM
Paul (pvnick gmail com) (3 replies)
Re: Bypassing of web filters by using ASCII Jun 22 2006 07:46AM
Amit Klein (AKsecurity) (aksecurity hotpop com) (1 replies)
RE: Bypassing of web filters by using ASCII Jun 23 2006 11:55AM
James C. Slora Jr. (james slora phra com) (3 replies)
Re: Bypassing of web filters by using ASCII Jun 26 2006 05:56PM
Hubert Seiwert (hubert westpoint ltd uk) (1 replies)
RE: Bypassing of web filters by using ASCII Jun 26 2006 07:31PM
James C. Slora Jr. (james slora phra com)
RE: Bypassing of web filters by using ASCII Jun 23 2006 10:12PM
RSnake (rsnake shocking com)
RE: Bypassing of web filters by using ASCII Jun 23 2006 07:23PM
Amit Klein (AKsecurity) (aksecurity hotpop com)
Re: Bypassing of web filters by using ASCII Jun 22 2006 03:40AM
Thor (Hammer of God) (thor hammerofgod com)
Re: Bypassing of web filters by using ASCII Jun 21 2006 11:23PM
Kurt Huwig (k huwig iku-ag de)
Paul schrieb:
> Very interesting, indeed. Does this work with functional characters
> such as html brackets? What about html tag obfuscation (bypassing
> script filters such as those in place at hotmail)?

This works for the whole set of ASCII characters. I was able to create a
HTML page where the MSB was set on all bytes of the file, i.e. also all
brackets, and it worked fine with IE.

I did not check hotmail's script filters.

> Nice find.

Thanks. I happened to read Wikipedia's ASCII page on my lunch time and
stumbled upon

"the eighth bit was commonly used as a parity bit for error checking on
communication lines or other device-specific functions. Machines which
did not use parity typically set the eighth bit to zero, though some
systems such as Prime machines running PRIMOS set the eighth bit of
ASCII characters to one."

Then I was curious what our browsers do with this. The hardest thing was
to get the test page up; the PrintWriter used by JSP deletes the MSB, so
I had to use a servlet.
--
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

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