Rule:  

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Sid:
488

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Summary:
This event is generated when a connection is closed from a resource
external to the protected network.

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Impact:
Unknown.

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Detailed Information:
This event indicates that an established connection has been closed
from a source external to the protected network. Since the external
connection port is 80, this is unusual behavior. It may be that an
attacker is using port 80 on the external machine to initiate a
connection to a machine on the protected network in an attempt to bypass
firewall protection. When this connection is terminated, this rule will
generate an event.

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Affected Systems:
	All systems
	
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Attack Scenarios:
An attacker can use port 80 from a compromised machine to connect to
another compromised host in an attempt to bypass firewall restrictions
by imitating normal web traffic.

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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:
Investigate the host for signs of system compromise.

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Contributors:
Original Rule Writer Unknown
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

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