Re: IDS evaluations procedures

[Adam Powers <apowers () lancope com>]

Tim, I hate to stir up this whole can of worms (pun alert) and yes I know
this is off topic but can you please qualify this seemingly non sequitur
statement?

"All IDS devices are subject to large numbers of false positives, which is
why if you're making a new investment you should consider IPS technology, as
this gives you a far lower TCO and real-world protection against zero-day
threats."

How so?

I really struggle with this whole "because it's inline it must be more
accurate" thing. Sure, if I turn off a bunch of sigs on the IPS that are
less reliable, accuracy will increase. But why not do the same thing on the
non-inline IDS?

Is there something magical about being inline that makes the system less
prone to false positives? If so, what?

----------

David, addressing your original question... (which, incidentally, was about
INTERNAL attack traffic, not Internet Storm Center quality stuff that's
randomly hitting the outside of your firewall), we'll need a few extra data
points.

1. What are you testing for? Traffic-based anomalies? Application level RFC
violations and anomalies? Relational-modeling anomalies?
Behavioral-anomalies?

2. What collection mechanism is employed? NetFlow? sFlow? Ethernet Frames?
Other?

3. Are you only interested in classic "attacks" (fire up Nessus, see what
happens) or other anomalies such as malfunctioning applications,
policy-driven anomalies, etc?





On 7/13/05 3:33 AM, "THolman () toplayer com" <THolman () toplayer com> wrote:

> Hi Dave,
>
> Take a peek at the Internet Storm Centre @ SANS -
>
> http://isc.sans.org/
>
> Gives you a good idea about what's going on.
> Which IDS devices are you looking at?  All IDS devices are subject to large
> numbers of false positives, which is why if you're making a new investment
> you should consider IPS technology, as this gives you a far lower TCO and
> real-world protection against zero-day threats.  It also saves you having to
> buy lots of IDS sensors, seeming a large proportion of the load will be
> absorbed and taken care of by the IPS.
> Just my 2 cents.. ;)
>
> Cheers,
>
> Tim
>
> -----Original Message-----
> From: Sames, David [mailto:David.Sames () sparta com]
> Sent: 13 July 2005 04:54
> To: THolman () toplayer com
> Subject: RE: IDS evaluations procedures
>
> Thanks for the info - those are exactly the kinds of characteristics I
> need to consider - at this point, I'm not evaluating a product per se -
> I'm evaluating some claims by some of our researchers :-) FP's are what
> I'm most concerned about. I'll check things out to see if I can get more
> stats - and of attempt to produce some data sets that may look like
> "anomalies" but are really traffic spikes and shouldn't be flagged.
>
> > >
>
> To specifically answer your question, look at current attack weather
> reports
> - you'll see approximately 15-20% of perimeter traffic is in fact worms
> trying to propagate.  Any evaluation should be designed with this in
> mind.
> ..but more importantly, make sure you're evaluating something that will
> do
> the job in hand and doesn't lead you up the garden path with inaccurate
> marketing collateral!  :)
> <<<
>
> That's exactly what I was looking for !
>
> Regards,
>
> Dave
>
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