Rule:
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Sid:
255

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Summary:
This event is generated when an attempt is made to request a zone 
transfer from a DNS Server

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Impact:
Information disclosure.

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Detailed Information:
DNS Zone transfers are normally used between DNS Servers to replicate 
zone information. Zone transfers can also be used to gain information 
about a network.

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Affected Systems:
	All DNS Servers

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Attack Scenarios:
A malicious user may request a Zone Transfer to gather information 
before commencing an attack.  This can give the user a list of hosts to 
target.

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Ease of Attack:
Simple.

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False Positives:
DNS Zone transfers may be part of normal traffic for DNS servers.

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False Negatives:  
None known

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Corrective Action:
Configure the DNS servers to only allow zone transfers from authorised 
hosts, limit the information available from publicly acessible DNS 
server by using Split Horizon DNS or separate DNS Servers for internal 
networks.

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Contributors:
Original rule writer unknown
Original document author unkown
Sourcefire Vulnerability Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

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