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 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/IDS184

--
