Snort mailing list archives
Re: Questions: Filtering ESP & Duplicate traffic
From: Jack Pepper <pepperjack () afferentsecurity com>
Date: Wed, 25 Mar 2009 16:39:02 -0500
Quoting Seth Art <sethsec () gmail com>:
As far as filtering out things like ESP and VPN traffic, I see no reason to inspect it if it's encrypted. (That's what encryption is for right? To make stuff unreadable?)
This is what I was thinking, although the pitfall that Jason Haar mentions is exactly the one i was thinking of... The "what if" at some point in the future an ESP based vulnerability is identified. I worry that even though the VRT team releases sigs, I am blind to the attack until I yank those bpf filters out.
I have picked up many HTTPS bofs with this rule: alert tcp $EXTERNAL_NET any -> $HOME_NET 443 (msg: "HTTPS overflow incoming"; flow: established; content:"AAAAAAAAAAAAAAAAAAAAAAA"; nocase; classtype:trojan-activity; sid: 2992007; rev:1;) based on the idea that "what is the liklihood of an "A"-sled showing up in encrypted traffic". It gets lots of hits, even now 3 years after the original OPENSSL defect was patched. I would seem economical and reasonable to look for a sled of nops or As in ESP traffic, because it just shouldn't ever happen. jp -- Framework? I don't need no stinking framework! ---------------------------------------------------------------- @fferent Security Labs: Isolate/Insulate/Innovate http://www.afferentsecurity.com ------------------------------------------------------------------------------ _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- Questions: Filtering ESP & Duplicate traffic Seth Art (Mar 24)
- Re: Questions: Filtering ESP & Duplicate traffic Joel Esler (Mar 24)
- Re: Questions: Filtering ESP & Duplicate traffic Jason Haar (Mar 24)
- Re: Questions: Filtering ESP & Duplicate traffic Seth Art (Mar 25)
- Re: Questions: Filtering ESP & Duplicate traffic Jack Pepper (Mar 25)
- Re: Questions: Filtering ESP & Duplicate traffic Jason Haar (Mar 24)
- Re: Questions: Filtering ESP & Duplicate traffic Joel Esler (Mar 24)