Rule:
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Sid:
245

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Summary:
This event is generated when an mstream handler attempts to identify active agents.

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Impact:
Severe. If the listed source IP is in your network, it may be an mstream handler.  If the listed destination IP is in your network, it may be an mstream agent.

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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.  There are "handler" hosts that are used to coordinate the attacks and "agent" hosts that launch the attack.  A handler can probe to see if an agent is active by sending it a UDP packet to destination port 10498 with a string of "ping" in the payload. 

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Affected Systems:
Any mstream compromised host.

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Attack Scenarios:
A mstream handler may probe to see if an agent is active.

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

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False Positives:
None Known.

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False Negatives:
There are other known handler-to-agent ports in addition to  10498.

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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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