Firewall Wizards mailing list archives
RE: Firewalls Compared
From: "Ben Nagy" <ben () iagu net>
Date: Thu, 1 Jul 2004 10:32:44 +0200
-----Original Message----- From: firewall-wizards-admin () honor icsalabs com [mailto:firewall-wizards-admin () honor icsalabs com] On Behalf Of Jim Seymour
[...]
But, you knowwhat the vulnerability looks like and could look at traffic and identify malicious activity even without signatures.I'm trying to reconcile "know what the vulnerability looks like" with "even without signatures," and failing miserably.
Well, a "buffer overflow vulnerability" looks like [stuff to fill up buffer].[code]. Per se, that's not a signature, but we can use it in several places to protect against not-yet-written attacks and not-yet-discovered vulnerabilities. For example if we know from the protocol rules that we're looking at any user supplied parameter. A format string vulnerability is pretty easy to spot - but if you can apply intelligent protocol context to where you look for it then you will do way better than using static signatures that just dump any packet with %n%n or %x or whatever. I think there's a word game here which might be confusing you - "signatures" are conflated with "looking for known attacks". In theory, you could call what I describe above a kind of signature, as well. It's just that "people" don't. :)
[...] Gartner, that organization's cache' has just taken a *major* hit in my eyes. Perhaps I'm missing/misunderstanding something. If so: Somebody kindly enlighten me? Jim
Sure - you mistakenly assumed that Gartner was more than a predictor of upcoming market trends, and was instead a predictor of intelligent technical advances. I feel kind of bad that we're all beating up Mr Stiennon again, though, since I actually think the core point he made is sound: "The future of network security is all about inspecting traffic" I'm going to start by unfairly straw-manning Devdas: "(generalisations follow, they might not be applicable everywhere) As I understand it proxies watch for known good traffic. They will filter out stuff which is not known to be good. IPS watches for known bad traffic. It only responds to that which is known to be bad. This is a lousy setup for a firewall. Firewalls MUST be in a default DENY mode." Now you're sounding curmudgeonly - reduce your dosage of Paul and mjr mails. ;) Sure, lots of people claim application intelligence, but they lie. Vendors do that, we're weasels. Face it - everybody is already taking a "pick out stuff that looks bad" approach to application inspection, nobody is doing "completely understand the protocol and enforce security rules at all points to avoid every attack". I bet five beers that that last proxy that fully understood a protocol and could take a protocol equivalent of "only known good" to completely sanitise the application was probably HTML for the SEAL, and it wouldn't work with what we call HTML today. The key to the "future == inspecting traffic" approach is that it's actually _doable_ in real life, unlike fully default deny secure firewalls that use full application knowledge - positing that the world will not soon move to the mjr sponsored model of "stop using OSes and applications that suck". This "future" is just about more flexible ways to identify a lot of malicious traffic - instead of trying to get it _all_, failing, sulking, and then completely opening up your security (which is what companies do today). As I said before, it's pretty much a matter of what colour you paint the box - IPS, Deep Inspection Firewall or Inspectotron Fireweasel. However - whatever you want to call it, it's a good approach, and it works. It is NOT a more secure approach than running secure apps, using OSes that don't suck, not letting users browse or receive attachments, and having oldschool firewalls. However, it's a lot more realistic. Cheers, ben _______________________________________________ firewall-wizards mailing list firewall-wizards () honor icsalabs com http://honor.icsalabs.com/mailman/listinfo/firewall-wizards
Current thread:
- Re: Firewalls Compared George Capehart (Jul 01)
- Re: Firewalls Compared Devdas Bhagat (Jul 02)
- <Possible follow-ups>
- RE: Firewalls Compared Bill Royds (Jul 01)
- RE: Firewalls Compared Ben Nagy (Jul 01)
- RE: Firewalls Compared Paul D. Robertson (Jul 01)
- RE: Firewalls Compared Marcus J. Ranum (Jul 02)
- Re: Firewalls Compared Devdas Bhagat (Jul 02)
- Re: Firewalls Compared Marcus J. Ranum (Jul 02)
- RE: Firewalls Compared Marcus J. Ranum (Jul 02)
- RE: Firewalls Compared Paul D. Robertson (Jul 01)