Rule: 

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Sid: 
111-2

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Summary: 
This event is generated when the pre-processor stream4
detects network traffic that may constitute an attack.

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Impact: 
Unknown. Possible attempt to close a session by a third party.

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Detailed Information:
This event indicates that the pre-processor stream4 has detected an out
of sequence packet with the RST flag set or a packet without the
required RST and ACK flags in a TCP session. This is abnormal behavior
and may constitute an attack or be an indicator of spurious activity on
a network.

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Affected Systems:
	All systems

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Attack Scenarios: 
An attacker may inject packets with the RST flag set into a session in
an attempt to close the session and cause a Denial of Service (DoS)
between server and client. This technique may also be used in session
hijacking attempts.

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Ease of Attack: 
Moderate.

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False Positives:
None Known.

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False Negatives:
None Known.

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Corrective Action:
Check the target host for signs of compromise.

Ensure the system is up to date with any appropriate vendor supplied patches.

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Contributors:
Martin Roesch <roesch@sourcefire.com>
Sourcefire Vulnerability Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

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