Snort mailing list archives
The lack of a "client" and "server" definition in snort...
From: Jason Haar <Jason.Haar () trimble co nz>
Date: Tue, 5 Jun 2001 20:03:13 +1200
I see lots of false positives on vision18.conf from rules such as: alert TCP $EXTERNAL any -> $INTERNAL 2301 (msg: "IDS244/http-compaq-insight-dot-dot"; content: "../"; classtype: I get false positives off events such as a user downloading a HTML page that references "<IMG SRC='../icons/xxx.gif'>". The client request goes from $INTERNAL port 2301 to $EXTERNAL port 80 - hence the match. However, that wasn't the intent of the rule. From left to right it's saying that if an EXTERNAL CLIENT on any port makes a TCP connection to port 2301 on an INTERNAL SERVER, then... Well, that's the way I read it :-) So, is such "stateful" matches possible? Is that what the stream2 preprocessor will eventually be used for? At the moment I assume it "only" (trying not to offend anyone ;-) bundles lots of packets within a TCP session to make them appear as one really large packet WRT rule matches? I don't know if such "handedness" actually exists in the rules, but a combination of "handedness" plus stream2 recording which host-port pair instigated a session would probably do what I'm describing? -- Cheers Jason Haar Unix/Special Projects, Trimble NZ Phone: +64 3 9635 377 Fax: +64 3 9635 417 _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: http://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- The lack of a "client" and "server" definition in snort... Jason Haar (Jun 05)
- Re: The lack of a "client" and "server" definition in snort... Jed Haile (Jun 05)
- Re: The lack of a "client" and "server" definition in snort... Jason Haar (Jun 06)
- Re: The lack of a "client" and "server" definition in snort... Jed Haile (Jun 05)