Rule:
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Sid:
249

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Summary:
The event is generated when a DDoS mstream client makes contact with an mstream handler.

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Impact:
Severe. If the listed source IP is in your network, it is possibly an mstream client.  If the listed destination IP is in your network, it is possibly an mstream handler.

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Detailed Information:
The mstream DDoS uses a tiered structure of compromised hosts to coordinate and participate in a distributed denial of service attack. At the highest level, clients communicate with handlers to inform them to launch attacks.  A client may contact a handler using a TCP SYN packet to destination port 15104.   

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Affected Systems:
Any mstream compromised host.

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Attack Scenarios:
After a host becomes an mstream handler, the client will attempt to communicate with the handler.

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Ease of Attack:
Simple. mstream code is freely available.

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False Positives:
A legitimate server port of 15104 will cause this rule to fire.  This rule may also generate a false positive if port 15104 is selected as an FTP data port.

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False Negatives:
There are other known client-to-handler ports in addition to 15104.

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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.

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Contributors:
Original rule writer unknown
Sourcefire Research Team
Judy Novak <judy.novak@sourcefire.com>

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Additional References:

CVE:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-0138

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