Rule:
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Sid:
231

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Summary:
This event is generated when a pong packet for the Trinoo (aka trin00) DDos suite is detected.

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Impact:
This may indicate a compromised system or be the prelude to a Distributed Denial of Service (DDoS) attack.

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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.

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Affected Systems:
 
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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.

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Ease of Attack:
Simple. Trinoo client and master programs are widely available.

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False Positives:
None Known

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False Negatives:
None Known

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Corrective Action:
Disconnect infected machine(s) from the network immediately.

Use software to determine if a host has been compromised using a
rootkit.

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Contributors:
Original rule writer unknown
Snort documentation contributed by Jon Hart <warchild@spoofed.org>
Sourcefire Vulnerability Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

SANS:
http://www.sans.org/newlook/resources/IDFAQ/trinoo.htm

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