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 Team Judy Novak <judy.novak@sourcefire.com> -- Additional References: CVE: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-0138 Arachnids: http://www.whitehats.com/info/IDS182 --
