full-disclosure - Re: Bypassing "smart" IDSes with misdirected frames? (long and boring)

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Message-ID: <20040528181906.P50588@dekadens.coredump.cx>
From: lcamtuf at ghettot.org (Michal Zalewski)
Subject: Re: Bypassing "smart" IDSes with misdirected
 frames? (long and boring)

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 --

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