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		 NetBSD Security Advisory 2011-001
		 =================================

Topic:		BIND DoS due to improper handling of RRSIG records


Version:	NetBSD-current:		affected prior to 20101203
		NetBSD 5.1:		affected prior to 20110111
		NetBSD 5.0:		affected prior to 20110111
		NetBSD 4.0.*:		affected prior to 20110124
		NetBSD 4.0:		affected prior to 20110124
		pkgsrc:			net/bind97 package prior to 20101203


Severity:	Denial of Service


Fixed:		NetBSD-current:		Dec 2nd, 2010
		NetBSD-5-1 branch:	Jan 10th, 2011
		NetBSD-5-0 branch:	Jan 10th, 2011
		NetBSD-5 branch:	Jan 6th, 2011
		NetBSD-4-0 branch:	Jan 23rd, 2011
		NetBSD-4 branch:	Jan 23rd, 2011
		pkgsrc net/bind97:	bind-9.7.2pl3 corrects this issue
		pkgsrc net/bind96:	bind-9.6.2pl3 corrects this issue

Please note that NetBSD releases prior to 4.0 are no longer supported.
It is recommended that all users upgrade to a supported release.


Abstract
========

Failure to clear existing RRSIG records when a NO DATA is negatively
cached could cause subsequent lookups to crash named.

This vulnerability has been assigned CVE-2010-3613 and CERT
Vulnerability Note VU#706148.


Technical Details
=================

Adding certain types of signed negative responses to the cache
doesn't clear any matching RRSIG records already in the cache.  A
subsequent lookup of the cached data can cause named to crash
(INSIST).

This vulnerability affects recursive nameservers irrespective of
whether DNSSEC validation is enabled or disabled.  Exploitation
requires a DNS client authorized to use the nameserver for recursion
requesting information about a specially prepared zone not on the
same nameserver.


Solutions and Workarounds
=========================

We suggest fixing this vulnerability by using the current net/bind97
pkgsrc package instead of the in-system bind until the entire system
can be updated (eg to the next security/critical release, or a binary
snapshot from http://nyftp.netbsd.org/pub/NetBSD-daily/ from past the
fix date).


Thanks To
=========

Thanks to the Internet Systems Consortium for reporting this
vulnerability.  Thanks to Christos Zoulas for fixing this issue in
- -current.  Thanks to Petra Zeidler for preparing the pullups to
fix this issue on the branches.


Revision History
================

	2011-02-01	Initial release


More Information
================

Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at 
  http://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2011-001.txt.asc

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/ .

Copyright 2011, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2011-001.txt,v 1.1 2011/02/01 22:03:34 tonnerre Exp $

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