Rule:

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Sid:
261

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Summary:
This event is generated by an attempted buffer overflow associated with improperly formatted DNS inverse queries. 

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Impact:
Severe. The DNS server can be compromised allowing the attacker access at the privilege level at which BIND runs.  

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Detailed Information:
Certain versions of BIND do no perform correct bounds checking when responding to an inverse query. A maliciously formatted inverse query can cause the DNS server to crash and allow remote access with the privileges of the user running BIND.  Inverse queries are disabled by default; this attack can affect DNS servers that have been configured to enable them.

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Affected Systems:
BIND 4.9 releases prior to 4.9.7 and BIND 8 releases prior to 8.1.2. 

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Attack Scenarios:
An attacker can launch this exploit to gain remote access to the DNS server.

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Ease of Attack:
Simple.  Code exists to exploit the buffer overflow.

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False Positives:
None Known

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False Negatives:
None Known

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Corrective Action:
Upgrade to a version of BIND that is not vulnerable to this attack.

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Contributors:
Original rule writer unknown
Sourcefire Research Team
Judy Novak <judy.novak@sourcefire.com>

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Additional References:

CERT:
http://www.cert.org/advisories/CA-1998-05.html


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