Re: Intrusion Detection Evaluation Datasets

On 13/03/2009 21.05, Paul Palmer wrote:

> So, for example, in some (well, at
> least one) IDS products, the signature writer can write a single
> signature to recognize attempts to exploit a vulnerability in a data
> structure embedded within a Quicktime Movie file even before he knows
> how the attacker will encode the exploit.

Paul, I think the IDS you're talking about is unique (so far), and I 
believe I know which one you're referring to :)
To go back to Terry's question, Paul's example shows something that you 
cannot really do right now with Snort. You would need to rewrite the 
detection engine from scratch, in particular the regular expression 
engine (I won't mention the details, but the whole thing is related with 
grammar and automaton theory).
We had a similar case when monitoring a network with an anomaly-based 
NIDS. Snort was able to detect only one instance of the attack, while 
the anomaly-based NIDS detected all the attack instances. To achieve the 
same detection rate with Snort, we should have written another 255 
rules...which would have make the whole system just run slower (and to 
detect just one attack!)...
Signature-based IDSs are moving towards vulnerability signatures, 
because their application is of great interest especially for IPS 
vendors. However, the power of vulnerability signatures has not been 
fully explored yet.

-- 
Damiano Bolzoni

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