Greetings to everyone. I have some questions about exploit-based and vulnerability-based signature of IDS.
I heard that exploit-based signature is dead (useless), since vulnerability-based signatures are more effective than exploit-based signatures in that they can detect unknown exploits if a vulnerability can be utilized by many exploits. However, I don't agree with this argument, for the following reasons: (1) When a vulnerability is unknown, exploit-based might be a good solution. (2) Exploit-based signatures are still irrepetable for early defense of zero-day worms or zero-day exploits, since exploit-based signatures can be generated more timely. (3) In the perfect world, we need to generate both types of signatures (even finally we only use vulnerability-based signature in detection). That way we not only know we were attacked, but we know with what type of exploit; or that it's a new unknown variant of an exploit. That's useful information in and of itself. To support the above viewpoints, I have some concrete questions needed to be answered: (1) Were there some attacks that have exploit-based signature but have not vulnerability-based signature? Can someone give me some exmples? (2) Were there some examples to show that exploit-based signatures were generated much quickly and timely than the generation of vulnerability-based signatures for the historical worms or attacks ? (3) Does current IDS (e.g. Snort) use both signature types of exploit-based and vulnerability? If so, what percentage of sigantures are exploit-based? Thanks for you any input of discussing "exploit-based vs. vulnerability-based signature" !