Snort mailing list archives
Funky packets
From: James Lay <jlay () slave-tothe-box net>
Date: Tue, 05 Mar 2013 08:46:45 -0700
Hey All! So...recently I got to packet capture first hand a rather extensive 2 day (unsolicited) recon/router test. Almost all of these packets were short on the TCP header: 13 2013-03-01 18:05:33.218358000 x.x.x.x -> x.x.x.x TCP 74 0 > 0 [FIN, RST, ACK, URG, ECN, CWR, Reserved] Seq=1 Ack=1 Win=6667 Urg=0 Len=12 15 2013-03-01 18:17:39.706664000 x.x.x.x -> x.x.x.x TCP 74 0 > 0 [FIN, SYN, PSH, ECN, CWR, NS, Reserved] Seq=3323674723 Win=6667[Malformed Packet] 16 2013-03-01 18:20:15.162110000 x.x.x.x -> x.x.x.x TCP 74 0 > 0 [SYN, CWR, NS, Reserved] Seq=0 Win=6667, bogus TCP header length (12, must be at least 20) 25 2013-03-01 19:49:34.199237000 x.x.x.x -> x.x.x.x TCP 74 0 > 0 [SYN, RST, ECN, NS, Reserved] Seq=0 Win=6667, bogus TCP header length (12, must be at least 20) 26 2013-03-01 19:49:34.199244000 x.x.x.x -> x.x.x.x TCP 74 0 > 0 [SYN, RST, ECN, NS, Reserved] Seq=0 Win=6667, bogus TCP header length (12, must be at least 20) 65 2013-03-02 00:00:15.431041000 x.x.x.x -> x.x.x.x TCP 74 0 > 0 [FIN, SYN, URG, ECN, Reserved] Seq=0 Win=5000, bogus TCP header length (8, must be at least 20) 66 2013-03-02 00:00:15.431092000 x.x.x.x -> x.x.x.x TCP 74 0 > 0 [FIN, SYN, URG, ECN, Reserved] Seq=0 Win=5000, bogus TCP header length (8, must be at least 20) these are just a few of the many I saw. I've created the below (SYN + RST packets are my favorite) to see at least some of this: alert tcp $EXTERNAL_NET 0 -> $HOME_NET 0 (msg:"SYN with RST packet"; flags:S,R; classtype:bad-unknown; sid:10000042; rev:1;) Interestingly, of the 24 packets that have SYN and RST, this rule only fires on 3. Both frag3 and stream5 have detect_anomalies set. Anyone else have any funky packet rules they'd like to share? Thanks! James ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Snort-sigs mailing list Snort-sigs () lists sourceforge net https://lists.sourceforge.net/lists/listinfo/snort-sigs http://www.snort.org Please visit http://blog.snort.org for the latest news about Snort!
Current thread:
- Funky packets James Lay (Mar 05)
- Snort, SCADA and DigitalBond Andrea Modesto Rossi (Mar 05)
- Re: Snort, SCADA and DigitalBond Joel Esler (Mar 05)
- Snort, SCADA and DigitalBond Andrea Modesto Rossi (Mar 05)