I would also like to add this simple question (and answer) to the mix.
What is the best way to evade an IDS?
Knowing what it looks for...
Open sigs for an IDS/IPS does more harm then good (for the majority) IMO.
IE a SKILLED attacker wants to attack my network, and i use an ids
that has an open sig set. Via posts on various mailing lists the
attacker has worked up a probability matrix of what products are being
used for IDS/IPS. So happens that those products have an open
signature set. Now all the attacker has to do is look at what those
systems deficiencies are (be it from a technical stand point, be it
from a sig stand point) and modify his attack to circumvent the
product that is put in place.
Those opens sigs sure did help in evading the protection put in place.
The best option IMO is having a skilled R&D team who is on the edge of
what is out there, a closed signature set, and the ABILITY to add your
own SIGNATURES from other sources (be it snort based rules only or
snort based rules + vendor based rule framework). All of a sudden
you then have the best of both worlds.
Oh and simple pattern matching is crap, there needs to be an
abstraction layer above the pattern matching that says "apply this
pattern if the following criteria have been meet {syn syn ack syn ack
*pattern* rst}" or something along those lines that are exploit
specific, be it flow information or protocol level flags or features.
Andre
On Tue, 15 Mar 2005 08:06:02 -0800, Andrew Plato
<andrew.plato@anitian.com> wrote:
1. I know ISS's language to some extent because I helped develop the
engine inside their product (I worked at Network ICE before ISS bought
them.) Some are simple pattern matches, many are not.
2. I am familiar with Snort's rules (although I do not profess to be an
expert). I also know that Snort's rules, while very powerful and
flexible, are WELL beyond the capability of 90% of the IT and network
admins in the world. Most organizations don't take the time (nor do they
have the time) to analyze signatures. They are more consumed with things
like productivity and performance. I know this from my experience (10+
years) as an IT consultant.
Thus my point - while seeing the details of a signature is fascinating
to security geeks, it is not terribly important to the vast majority of
IT admins. As such, I don't think the ability to see signature specs is
an important measure of the value of an IPS/IDS product. It may be
important to security nerds, but the general IT/network admin population
doesn't care that much. And frankly, products that do show their
signature details are rarely changed anyways.
___________________________________
Andrew Plato, CISSP
President/Principal Consultant
ANITIAN ENTERPRISE SECURITY
3800 SW Cedar Hills Blvd, Suite 280
Beaverton, OR 97005
503-644-5656 Office
503-214-8069 Fax
503-201-0821 Mobile
www.anitian.com
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GPG public key available at: http://www.anitian.com/corp/keys.htm
-----Original Message-----
From: Joshua Berry [mailto:jberry@PENSON.COM]
Sent: Tuesday, March 15, 2005 6:50 AM
To: Andrew Plato; Stephane; rick.brady@libertymutual.com
Cc: focus-ids@securityfocus.com
Subject: RE: How to choose an IDS/FW MSS provider
Since you can't see the signature, how do you know they aren't doing
simple string matching? Second, obviously you aren't very familiar with
Snort's rule language, it isn't just simple string matching, there is a
*ton* of other logic available to reduce false positives/negatives.
Snort also has conveniently had support for PCRE matching for a long
time now.
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