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Vulnerability Note VU#734644ISC BIND 8 vulnerable to cache poisoning via negative responsesOverviewThe BIND 8 name server contains a cache poisoning vulnerability that allows attackers to conduct denial-of-service attacks on specific target domains.I. DescriptionSeveral versions of the BIND 8 name server are vulnerable to cache poisoning via negative responses. To exploit this vulnerability, an attacker must configure a name server to return authoritative negative responses for a given target domain. Then, the attacker must convince a victim user to query the attacker's maliciously configured name server. When the attacker's name server receives the query, it will reply with an authoritative negative response containing a large TTL (time-to-live) value. If the victim's site runs a vulnerable version of BIND 8, it will cache the negative response and render the target domain unreachable until the TTL expires.II. ImpactAttackers may conduct denial-of-service attacks on specific target domains by enticing users to query a malicious name server.III. SolutionUpgrade BINDThe ISC has prepared BIND 8.3.7 and BIND 8.4.3 to address this vulnerability. Name servers running BIND 4 are not affected. To obtain the latest versions of BIND, please visit Apply a patch or updated version from your vendor Many operating system vendors include BIND with their products and will be preparing new versions to address this vulnerability. For a list of vendors that the CERT/CC has received information from regarding this vulnerability, please see the Systems Affected section of this document. Systems Affected
References
The CERT/CC thanks the Internet Software Consortium for bringing this vulnerability to our attention. This document was written by Jeffrey P. Lanza.
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