Re: IDS thoughts

[Ramani Yellapragada <ryellapr () masaka cs ohiou edu>]

> "Anomaly detection" isn't an architecture or implementation. It's no
> more "rate over time, cross host cross protocol" than it is "validate
> against RFCs". Anomaly detection is the philosophy of design that says
> that we can find interesting events by looking for deviations from the
> norm.
 
 But what are the common approaches to build upon this design idea? Say if we
 are looking at anomalies for a protocol. Then we could be looking at certain
 standard protocols(say ssh, smtp etc), learn their norm and look for
 deviations. But what if the anomaly is happening on another never used
 protocol. What if we had not looked at the norm for that protocol? Doesn't
 anomaly detection then boil down to signature-based method? Are there ways by
 which we can study deviations on general network traffic?
  
> The real fallacy here (and I'm not saying it's in your argument) is the
> idea that one system is going to address the whole network security
> policy --- at least, any time soon. This attitude has some
> organizations trying to solve internal security problems by monitoring
> for RPC vulnerabilities, while ignoring the innocuous-looking
> transactions occurring between a secretary and the CVS server.
  
 I feel this is the real problem that needs to be solved. Is there a way we
 can detect an anomaly regardless of what the protocol is? Or should we be
 looking only at protocols which are known to contain vulnerablities? How
 could anomaly-based detection help in this case?
  
Ramani.
   



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