Rule: 

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Sid:
1293

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Summary: 
This event is generated when traffic indicating Nimda worm activity is detected.

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Impact:
Possible infection by the Nimda virus.

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Detailed Information:
Nimda spreads by file infection, mass emailer, file share, or IIS unicode exploit to attack unpatched systems.

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Affected Systems:
Windows 95
Windows 98
Windows ME
Windows 2000

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Attack Scenarios:
An unpatched server is connected to the internet and is infected or an infected email is opened. Once infected the worm spreads itself.

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Ease of Attack:
Simple

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False Positives:
None known

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False Negatives:
None known

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Corrective Action:
Check the suspect host for signs of infection. Apply patches or upgrade the operating system

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Contributors:
Snort documentation contributed by Timothy Vienneau
Sourcefire Vulnerability Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

Microsoft:
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/topics/virus/nimda.asp

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