Rule:  
 
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Sid:
627

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Summary:
This event is generated when the Cybercop vulnerability scanner is used against a host.

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Impact:
Cybercop can be used to identify vulnerabilities on host systems.

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Detailed Information:
This particular packet is a part of Cybercop's OS identification. Specially crafted packets are able to elicit different responses from different operating systems.  This packet is likely to be part of a full Cybercop scan rather than an isolated event. Having SYN, FIN, URG and reserve bits 1 and 2 set at the same time is abnormal.

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Affected Systems:
All

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Attack Scenarios:
Cybercop can be used by attackers to determine vulnerabilities present on a host or network of hosts that could be used as attack vectors.

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Ease of Attack:
Simple

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False Positives:
This tool can be used legitimately by system and network administrators. Other vulnerability scanners may display the same behavior.

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False Negatives:
None known.

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Corrective Action:
TCP packets with SYN, FIN, URG and reserved bits 1 and 2 set at the same time are abnormal, use a packet filtering firewall to block them.

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Contributors:
Original Rule Writer Unknown
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>
Snort documentation contributed by Steven Alexander<alexander.s@mccd.edu>

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Additional References:

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