Snort mailing list archives
RE: Who doesn't care about virus rules, and why?
From: "Williams Jon" <WilliamsJonathan () JohnDeere com>
Date: Thu, 6 Nov 2003 11:12:48 -0600
<grin> When I had to do this, we didn't have the snort version with thresholding options in it, so I did it the old-fashioned way. I wrote a perl script that runs from cron every 5 minutes. It keeps track of the number of lines seen so far and ignores everything but new entries in the tcpdump file. It does the thresholding via in-memory hashes, and then generates an SMTP message if a source address crosses the threshold. Since we've got multiple instances of snort running and one dedicated to monitoring this type of traffic, when I've got a new thing I'm looking for (i.e. CyberKit pings instead of TCP 135 connects), I add the rule to that instance and my X dests/Y time stuff just includes it. I plan on playing with thresholding in the future, but so far, the job has kept me from playing :-( Jon -----Original Message----- From: Snortty [mailto:cwcwcwg () yahoo com] Sent: Thursday, November 06, 2003 10:38 AM To: Iain Hallam; Williams Jon Cc: snort-sigs () lists sourceforge net; snort-users Subject: Re: [Snort-users] Who doesn't care about virus rules, and why? Yes, William, Would you mind posting your rules to illustrate the point please? One objective for our snort IDS to be installed on our network backborne is to be faster in respond to the worm incidents like those ones occurred recently and it would help great deal if your way really works. Thanks in advance. S.W. --- Iain Hallam <ccidsh () swarfega plus com> wrote:
Williams Jon wrote:What we've ended up doing is monitoring thedefault route path forour network and watching for either TCP SYNs thatare going placesthey shouldn't or TCP RST packets generated eitherby the firewall orthe odd host that is actually hit. Withthresholding, we cangenerate fairly useful alerts in cases where, inBlaster's case, onesource address sends out TCP port 135 SYN packetsto more than Xnumber of hosts in Y period of time. This is soreliable, in nearlyevery case we've used it on, that we are able toauto-generate emailalerts that go to someone else to actually _deal_with the problemrather than making the IDS staff track down andcall each victimindependantly.We're doing something similar with ICMP on our network, but how can you tell the difference between large numbers of hosts and large numbers of packets to a single host? Would you mind posting one of your rules to illustrate the point? Thanks, Iain.
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Current thread:
- RE: Who doesn't care about virus rules, and why? Williams Jon (Nov 06)
- Re: Who doesn't care about virus rules, and why? Iain Hallam (Nov 06)
- Re: Who doesn't care about virus rules, and why? Snortty (Nov 06)
- RE: Who doesn't care about virus rules, and why? Jason Haar (Nov 06)
- <Possible follow-ups>
- RE: Who doesn't care about virus rules, and why? Schmehl, Paul L (Nov 06)
- Re: Who doesn't care about virus rules, and why? kenw (Nov 06)
- RE: Who doesn't care about virus rules, and why? Williams Jon (Nov 06)
- Re: Who doesn't care about virus rules, and why? Iain Hallam (Nov 06)