Some DNS servers respond with an inappropriate error message if queried for nonexistent AAAA records, which can lead to possible denial of service.
Some DNS servers respond with a "Name Error" response code (NXDOMAIN, RCODE 3) instead of "No Error" (RCODE 0) when queried for a nonexistent AAAA record. (AAAA records are used to provide name-to-address resolution for IPv6 addresses, as described in RFC1886.)
When an NXDOMAIN response code is received, the querying resolver will usually stop attempting to resolve that name. Resolvers that support negative caching (RFC2308) and receive an NXDOMAIN response will not query for A records for the same resource until the negatively cached error response has expired.
An attacker could create a localized denial-of-service condition by exploting this vulnerability.
Apply a patch from your vendor.
Cisco Systems Inc.
This document was written by Allen D Householder.
|Date First Published:||2003-03-26|
|Date Last Updated:||2003-05-23 13:46 UTC|