RE: Rule based vs. Signature based detection engine

["Tom Fulton" <tfulton9909 () comcast net>]

I want to understand this difference for a paper I am writing.

Can you explain "multi-conditioned, and can have data-dependant byte jumps,
etc."

I am but a mere mortal.

Thanks...

-----Original Message-----
From: snort-users-admin () lists sourceforge net
[mailto:snort-users-admin () lists sourceforge net] On Behalf Of Matt Kettler
Sent: Tuesday, July 20, 2004 10:04 PM
To: Tom Fulton; snort-users () lists sourceforge net
Subject: Re: [Snort-users] Rule based vs. Signature based detection engine


At 10:50 PM 7/20/2004, Tom Fulton wrote:
> The Snort 2.0 book by Jay Beale, et. al., (p. 142) explains that Snort 
> is
> rules-based, "which collects and correlates packets based on rules" and 
> that this is better than a signature engine which is nothing more than a 
> "definition of an attack".  Can anyone expand on this clarification?  I'm 
> under the impression that a rule in a *.rules file is basically a 
> "signature".  Do you think Jay is referring to the ability to have 
> pre-processor plug-ins that can normalize data before running against the 
> signatures (sorry, I mean rules)?  Aren't they basically the same thing 
> when it comes right down to it?

I think the comparison here is between something purely text-match-only as 
being a "signature" but snort rules are multi-conditioned, and can have 
data-dependant byte jumps, etc.



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