Rule: 

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Sid: 
100000111

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Summary: 
This event is generated when the Dabber virus attempts to exploit a 
vulnerability in the FTP server installed by the Sasser virus.

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Impact: 
If the Sasser virus is currently running on the affected system, then the 
Dabber virus will be able to install itself as well.

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Detailed Information:
Some variants of the Sasser virus install an FTP server that listens on port 
1023. However, this FTP server suffers from a buffer overflow in the PORT 
command, which can be exploited with a command of 100 or more characters. The 
Dabber virus makes use of this vulnerability as an infection vetor.

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Affected Systems:
Any machine with a variant of the Sasser virus whose FTP server listens on port 
1023. 

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Attack Scenarios: 
A known virus scans the Internet in search of vulnerable systems.

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Ease of Attack: 
Simple, as the virus is in the wild.

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False Positives:
None Known.

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False Negatives:
None Known.

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Corrective Action: 
Users should employ a virus removal tool to clean their system of both Dabber 
and Sasser, and then apply the latest security patches from Microsoft to 
prevent further infections.

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Contributors: 
Matt Watchinski <mwatchinski@sourcefire.com>
Alex Kirk <alex.kirk@sourcefire.com>

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Additional References:

http://www.microsoft.com/technet/security/bulletin/MS04-011.mspx

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