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Re: [Full-Disclosure] Re: Bypassing "smart" IDSes with misdirected frame

from [Michal Zalewski] Network Security [Permanent Link]
Subject: Re: [Full-Disclosure] Re: Bypassing "smart" IDSes with misdirected frames? (long and boring)
Date: Fri, 28 May 2004 18:21:39 +0200 (CEST) 
On Fri, 28 May 2004, Jim Bauer wrote:


The IDS will see not see a valid response to the "DATA" command (that is
never received) so it will know it is still in SMTP command mode.  Even
if your not-so-smart IDS let this slip by, there is still the issue of
"DEBUG" not being in a valid format for a header.


Which is precisely what I stated in the next paragraph. This is a naive
example, but illustrates w far broader and non-SMTP-specific problem quite
well. There are various protocols or attack vectors that do not involve
challenge-response communications (even the problem of distinguishing
between message body and message headers can be an example).

Cheers,
-- 
------------------------- bash$ :(){ :|:&};: --
 Michal Zalewski * [http://lcamtuf.coredump.cx]
    Did you know that clones never use mirrors?
--------------------------- 2004-05-28 18:19 --

   http://lcamtuf.coredump.cx/photo/current/
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