IDS mailing list archives
RE: Alarm response strategies
From: Frank Knobbe <frank () knobbe us>
Date: Mon, 26 Jul 2004 17:51:29 -0500
On Sun, 2004-07-25 at 20:35, Rob Shein wrote:
Given the fact that IDS are prone to false alarms (and easy to make trigger with spoofed traffic), it's the general consensus that active responses are a bad idea. For example, if I were to start scanning your network, and find myself suddenly blocked at the router or firewall, I would then spoof tons of UDP traffic from DNS servers that I believed you might use. Your firewall would then block traffic from them, and bingo, I've just shut down your ability to resolve things.
How does the inline-type IDS differ then? Or are you under the impression that your spoofed traffic gets blocked both ways? Why shouldn't a system be able to block unsolicited inbound packets, but let traffic that initiated from the inside out through without blocking it? (Oh wait... that's a normal stateful firewall then, right?) My point is, you can have reactive systems. They just have to be implemented in a smart fashion so that silly "default attack scenarios" don't create the DoS of the older days reactive systems. Once you have a smart reactive system, it will behave like the inline IPS. Except that it is reactive (doesn't block first packet). But the advantage is that you can react from more than one traffic monitoring point. With inline devices you are limited to that one choke point. Reactive devices can be triggered by sensors from all over your network. That should be the main differentiator between those systems, not the intelligence (or lack of) behind it. Regards, Frank
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Current thread:
- Alarm response strategies (infor) urko zurutuza (Jul 25)
- RE: Alarm response strategies Rob Shein (Jul 26)
- Re: Alarm response strategies David W. Goodrum (Jul 27)
- Re: Alarm response strategies Tony Carter (Jul 27)
- RE: Alarm response strategies Frank Knobbe (Jul 27)
- RE: Alarm response strategies Rob Shein (Jul 27)
- Re: Alarm response strategies David W. Goodrum (Jul 28)
- RE: Alarm response strategies Frank Knobbe (Jul 28)
- RE: Alarm response strategies Rob Shein (Jul 26)
- <Possible follow-ups>
- RE: Alarm response strategies Joshua Berry (Jul 27)
- RE: Alarm response strategies Richard Bejtlich (Jul 28)
- RE: Alarm response strategies Joshua Berry (Jul 28)