RE: IPS comparison

["Joseph Hamm" <jhamm () lancope com>]

> - I agree that "anomaly detection" != "zero day" detection. Just
because
>   my DNS server starts to connect to all the other hosts on my
network,
>   doesn't mean it has got a worm on it. 

It might if your DNS server doesn't normally do this.  Consider a
network anomaly detection system that profiled your network and created
unique usage/behavioral profiles for each host (including Ron's DNS
server).  You've told the box how your internal address space is defined
so now the box also knows your network's "dark" or unused address space.

(Defined internal address space) - (active hosts seen) = Unused or
"Dark" IP space

Now consider that your DNS server gets infected with a new worm and
starts scanning nearby hosts.  A smart NADS (network anomaly detection
system) will be able to quickly determine that this host is scanning
your dark address space (honeynet concept).  Any activity being directed
at this unused space can be assumed to be suspect.  

Also, consider the port being used.  If this is not a port that the DNS
server normally uses, then that would be suspect as well.  Not to
mention all of the tcp resets or icmp port unreachables (in the case of
UDP) that the DNS server will receive as it scans across your network.

Check out the whitepapers published by NADS vendors that outline cases
where new "zero-day" worms were detected before signatures became
available.  I agree that marketing departments squeeze all they can out
of zero-day, but I can at least vouch that our SteatlhWatch products
detected Zotob (and its variants) without the need for any signature
updates.  This means customers had early detection before signatures
were available.  I'm sure there are some other vendors out there that
can report the same.  Even signature based solutions can tout this if
they write sigs for the vulnerability as opposed to the exploit.

Joe


Joe Hamm, CISSP
Senior Security Engineer
Lancope, Inc.
jhamm () lancope com
404.644.7227  (cell)
770.225.6509   (fax)

Lancope - Security through Network Intelligence(tm)
StealthWatch(tm) by Lancope, a next-generation network security
solution, delivers behavior-based intrusion detection, policy
enforcement and insightful network analysis.  Visit www.lancope.com.


-----Original Message-----
From: Ron Gula [mailto:rgula () tenablesecurity com] 
Sent: Monday, August 29, 2005 8:56 PM
To: Focus-Ids Mailing List
Subject: Re: IPS comparison

At 06:01 PM 8/29/2005, Stefano Zanero wrote:
> Daniel Cid wrote:
> > This "anomaly" detection will only detect 0-day exploits for known 
> > vulnerabilities.
>
> A zero-day exploit is a curious marketing thing. You suddenly redefine 
> a difficult problem (catching zero-days) as a rather simpler problem 
> (create signatures that actually describe the vulnerability, which is 
> what any signature worth your licensing cost should do).
>
> So, presto!, you can rush up and put out some rather nice marketing 
> material on it.
>
> Fact is, anomaly detection is so rare that it's almost unexistant in 
> the commercial products, except for limited forms of "protocol anomaly 
> detection" and for Arbor's peakflow technology.

Two comments here.

- lot's of NIDS that tend to code for a vulnerability, don't actually
   code for the vulnerability. They are still writing attack signatures.
   The attack signatures are smarter than what was standard about five
   years ago, but I've yet to really see a NIDS come out of the box
   with full vuln/IDS correlation.

- I agree that "anomaly detection" != "zero day" detection. Just because
   my DNS server starts to connect to all the other hosts on my network,
   doesn't mean it has got a worm on it.

Ron Gula, CTO
Tenable Network Security


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