Firewall Wizards mailing list archives

Re: Corporate H/N IPS


From: Fritz Ames <fritzames () earthlink net>
Date: Sun, 15 Dec 2002 10:57:27 -0500

I have two concerns, promises and promises. Is it consesus that "Intrusion Prevention System" is a term devised to create a market--instead of creating a solution to a problem in order to satisfy a market? (It *is* cheaper to dream of product-differentiating terms, and feature names, than to actually make products accomplish anything that would be differentiating.) Is it also agreeable to say that application proxies are harder to support and administer than packet filters? Is it still fact that IDS's need a lot expertise, care, and feeding to avoid their being turned off or ignored? Don't "IPS" vendors pitch their solutions as being superior because they can do what IDS's and application-level firewall's can do? I feel that I have been told that products falling in the "IPS" category will cure all of my ills with no significant burden to keep them going, despite the fact that they combine two worlds that require expertise and to install and maintain. (My experience keeps failing me, as I find them a lot of work. 'Could just be me, and not being able to devote my time to them 100%.) The promises of new "product categories" like IPS's appear only good for obfuscation of what products actually do--therefore making competition on function and price much more difficult. The false promises by some also make it more difficult for legitimate and solid innovations to compete (because they are competing with vaporware or marketingware or, more accurately, lies.) So, what to do? Am I wrong?


Thank you,

Fritz

(Sorry for offering kerosene without offering solutions, but I have to start somewhere...)




Crispin Cowan wrote:
Talisker wrote:

Crispin
I'm not exactly in agreement with many of your points

No worries; that's what forums like this are for :)

EXACTLY like a firewall, only they look at higher level aplication
protocols than classic packet filtering firewalls.

I for one would not entrust my perimeter defense to a NIPS, however I may
consider using a NIPS to look for intrusion signatures on those packets that
have been passed by the firewall.  I feel they complement each other very
well.

Neither would I. I'm not saying that products marketed as NIPS make *good* firewalls. In particular, they are incomplete firewalls, because they don't have the classical capability to block on IPs, ports, & such. Conversely, one could also say that classical packet filters are also incomplete, because they don't look at high level application traffic. The composition of the two adds value to make a more complete firewall system.

None of which is new: ancient firewall design calls for an outer firewall defend your DMZ, and an inner firewall to defend your LAN. These firewalls would often be of different design, e.g. a packet filter on the outside and a proxy firewall on the inside.

To be clear, my claim is not that NIPS suck. My complaint is that the claim that NIPS is a bold new concept is crap, and that NIPS should properly be understood as an incremental improvement in firewall technology.

I do see HIPS as different from Secure OS's they are more widely
available to all, deployable with minimal impact on an existing network and
enterprise aware out of the box.

Again, this is an incremental improvement on an old concept. A retro-fit security enhancement package fitted onto an existing OS to make it a secure OS. Olde schoole secure OS people will rant about how much less cost-effective it is to retro-fit security, and they may be right, but that's what it is. We built one (Immunix) because I thought it was interesting, and because the economics of the cost of wholesale replacement of operating systems dwarf the cost benefits of designing in security vs. retrofitting it.

True: "intrusion detection" is what you call it when your detector is so
slow or imprecise that it cannot be used for prevention.

IDS can be a little hit and miss, I've had to switch some off because they
were so inadequate.  However, I have also used others to good effect they
have saved my network on many occasions.

Again, I'm not saying that IDS has no value, just that its value needs to be understood. Both Intrusion Preventers and Intrusion Detectors are looking at traffic/operations, and trying to distinguish good from bad. If the distinction can be done precisely (nearly zero false positives) and in real time (before the traffic/operation completes) then it can be used for access control. If the distinction is heuristic (has a real false positive rate) or is slow (makes the distinction long after the traffic/operation completes) then you use it for detection instead of prevention.

The trade off for detection is that detectors can detect much more subtle intrusions. They can infer attacks comprised of legitimate operations that would have passed access control. They can spend more time on analysis. This is why you have detection in addition to your access controls/prevention stuff.

Crispin



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