GEN:SID 1:231
Message DDOS Trin00 Daemon to Master message detected
Summary This event is generated when a pong packet for the Trinoo (aka trin00)
DDos suite is detected.
Impact This may indicate a compromised system or be the prelude to a
Distributed Denial of Service (DDoS) attack.
Detailed Information Once a Trinoo client has been installed on a compromised machine and a master is
ready and listening, the master sends a "png" (ping) command to its drones in
an attempt to enumerate the drone network. A functioning client will respond to
port 31335/udp with the text "PONG".

Once a machine becomes part of a trin00 network, a Denial of Service (DoS)
is typically initiated against one (or more) victim machines.
Affected Systems  
Attack Scenarios As part of a large scale attack against a machine or a network, an
attacker will compromise large numbers of machines which will form the
army that the trin00 master daemon will command.  The master daemon
typically instructs the clients to send mass-quantities of packets to
a set of victim hosts.  If the traffic is sufficient, the victim
machines will become resource deprived and thus endure a DoS condition.
Ease of Attack Simple. Trinoo client and master programs are widely available.
Corrective Action Disconnect infected machine(s) from the network immediately.

Use software to determine if a host has been compromised using a
rootkit.
Additional References SANS:
http://www.sans.org/newlook/resources/IDFAQ/trinoo.htm
Rule References arachnids: 186