Rule:

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Sid:
1239

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Summary:
This event is generated when an attempt is made to execute the RFParalyze DoS
exploit.

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Impact:
If the destination machine is vulnerable, it may start behaving
unpredictably.  Succesful exploitation may lead to a full system crash 
or may cause certain services to become unavailable.

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Detailed Information:
This signature triggers on execution of RFParalyze, an exploit written 
in 2000 by Rain Forest Puppy.  It was based on a binary exploit called 
"whisper", which was used in the wild at that time.  This exploit 
performs a NetBIOS session request with a source host of NULL, which is 
incorrectly handled by Windows 95/98 hosts.

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Affected Systems:
	Windows 95
	Windows 98

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Attack Scenarios:
An attacker can crash critical machines, thereby
preventing them from being accessed by legitimate clients.

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Ease of Attack:
Simple.  Exploit code exists.

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False Positives:
None known.

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False Negatives:
Potential future versions of this exploit, which may use
different message strings, will not be detected by this rule.

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Corrective Action: 
Patches are not available from the vendor.

Use a packet filtering firewall to block inbound traffic to port 139/TCP from
all untrusted networks & hosts

Upgrade critical machines to a more recent and supported version of the
operating system.

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Contributors:
Snort documentation contributed by Maarten Van Horenbeeck (maarten@daemon.be)
Original Rule Writer Unknown
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

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