Vigil@nce - BIND: denial of service via a Trust Anchor
September 2010 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/
SYNTHESIS OF THE VULNERABILITY
When BIND uses several Trust Anchors, one of them can send an invalid answer, in order to stop BIND.
Creation date: 15/09/2010
DESCRIPTION OF THE VULNERABILITY
The DNSSEC extension authenticates DNS packets, using a signature. A Trust Anchor is an authority publishing a root signature.
ISC proposes DLV (DNSSEC Look-aside Validation) providing an alternative Trust Anchor, which is configured in the named.conf file of BIND : dnssec-lookaside . trust-anchor dlv.isc.org.;
BIND can be configured with several Trust Anchors. However, in this case, if a Trust Anchor sends a message with an invalid signature, an error occurs in BIND, and it stops.
When BIND uses several Trust Anchors, one of them can therefore send an invalid answer, in order to stop BIND.
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