Vigil@nce - ISC BIND: denial of service via RPZ and RRSIG
May 2011 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/
SYNTHESIS OF THE VULNERABILITY
An attacker can send a signed query for a Response Policy Zone, in
order to stop ISC BIND.
Severity: 2/4
Creation date: 06/05/2011
IMPACTED PRODUCTS
– ISC BIND
DESCRIPTION OF THE VULNERABILITY
The DNS protocol defines the RRSIG type which contains the
signature of Resource Records located in the Answer and Authority
sections.
BIND version 9.8.0 supports RPZ (Response Policy Zone) which are
used by a recursive server to alter replies returned to the user.
The rpz_find() function of the bin/named/query.c file locates RPZ
entries to alter. However, this function is not conceived to
handle a query of type RRSIG/SIG. The INSIST() macro is thus
called, and an assertion error stops the server.
An attacker can therefore send a signed query for a Response
Policy Zone, in order to stop ISC BIND.
ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN
http://vigilance.fr/vulnerability/ISC-BIND-denial-of-service-via-RPZ-and-RRSIG-10619