Rule:--Sid:228--Summary:This event is generated when a Tribe Flood Network (TFN) Distributed Denial of Service (DDoS) client communicates with the TFN handler daemon to spawn a shell.--Impact:Attempted DDoS.  If the listed source IP is in your network, it may be a TFN client.  If the listed destination IP is in your network, it may be a TFN handler daemon.--Detailed Information:The TFN DDoS uses a tiered structure of compromised hosts to coordinate and participate in a distributed denial of service attack. Clients communicate with daemons to direct them to launch attacks. A client will communicate with a daemon to spawn a shell via an ICMP echo reply with an ICMP identification number of 456 and an ICMP sequence number of 0.  --Affected Systems:Any TFN compromised host.--Attack Scenarios:After a host becomes a TFN client, it will attempt to communicate with other TFN handler daemons.--Ease of Attack:Simple. TFN code is freely available.--False Positives:It is possible that this is a legitimate echo reply to a previous echo request that had an ICMP identification value of 456 and an ICMP sequence number of 0.  --False Negatives:None Known.--Corrective Action:Perform proper forensic analysis on the suspected compromised host to discover the means of compromise.Rebuild a confirmed compromised host.Use a packet-filtering firewall to block inappropriate traffic to the network to prevent hosts from being compromised.--Contributors:Original rule written by Max Vision <vision@whitehats.com>Sourcefire Research TeamJudy Novak <judy.novak@sourcefire.com>--Additional References:CVE:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-0138Arachnids:http://www.whitehats.com/info/IDS184--