Rule:--Sid:238--Summary:This event is generated when a Tribe Flood Network (TFN) Distributed Denial of Service (DDoS) daemon responds to a client request to spawn a shell.--Impact:Attempted DDoS.  If the listed source IP is in your network, it may be a TFN daemon.  If the listed destination IP is in your network, it may be a TFN client.--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 inform them to launch attacks. A daemon will respond with a client request to spawn a shell with an ICMP echo reply with an ICMP identification number of 123, an ICMP sequence number of 0 and a string of "shell bound to port" in the payload.   --Affected Systems:Any TFN compromised host.--Attack Scenarios:After a host becomes a TFN daemon, it will respond to client requests.--Ease of Attack:Simple. TFN code is freely available.--False Positives:None Known.--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/IDS182--