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		 NetBSD Security Advisory 2009-013
		 =================================

Topic:		BIND named dynamic update Denial of Service vulnerability

Version:	NetBSD-current:		affected prior to 2009-07-29
		NetBSD 5.0:		affected
		NetBSD 4.0.*:		affected
		NetBSD 4.0:		affected
		pkgsrc:			bind package prior to 9.5.1pl3 and 9.6.1pl1

Severity:	Denial of Service

Fixed:		NetBSD-current:		July 28, 2009 21:13 UTC
		NetBSD-5-0 branch:	July 28, 2009 22:26 UTC
		NetBSD-5 branch:	July 28, 2009 22:26 UTC
		NetBSD-4-0 branch:	July 28, 2009 22:19 UTC
		NetBSD-4 branch:	July 28, 2009 22:19 UTC
		pkgsrc 2009Q2:		bind-9.5.1pl3 and bind-9.6.1pl1 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
========

An assertion failure in the Berkeley Internet Name Domain server
software shipped in NetBSD can be used by a remote attacker to
cause the server process to crash by sending specially crafted
dynamic update messages.

This vulnerability has been assigned CVE-2009-0696 and CERT
Vulnerability Note VU#725188.


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

An error handling dynamic DNS update packets with the record data
type being set to "ANY" will cause an assertion in the
dns_db_findrdataset() function to trigger, causing the name server
to exit. This requires at least one of the record set entries
specified in the update to exist on the local server.

The assertion triggered will typically cause the following message:

  db.c:659: REQUIRE(type != ((dns_rdatatype_t)dns_rdatatype_any)) failed
  exiting (due to assertion failure). 

Note that this assertion will be triggered even if dynamic DNS
updates are disabled.


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

In order to avoid this vulnerability, either filter incoming dynamic
DNS update requests using a firewall or upgrade your bind software
to a non-vulnerable version.

The following instructions describe how to upgrade your bind binaries
by updating your source tree and rebuilding and installing a new
version of bind.

* NetBSD-current:

	Systems running NetBSD-current dated from before 2009-07-28
	21:13 UTC should be upgraded to NetBSD-current dated
	2009-07-28 21:13 UTC or later.

	The following files/directories need to be updated from the
	netbsd-current CVS branch (aka HEAD):
		external/bsd/bind/dist

	To update from CVS, re-build, and re-install bind:
		# cd src
		# cvs update -d -P external/bsd/bind/dist
		# cd external/bsd/bind/bin/named
		# make USETOOLS=no cleandir dependall
		# make USETOOLS=no install

* NetBSD 5.*:

	Systems running NetBSD 5.* sources dated from before
	2009-07-28 22:26 UTC should be upgraded from NetBSD 5.*
	sources dated 2009-07-28 22:26 UTC or later.

	The following files/directories need to be updated from the
	netbsd-5 or netbsd-5-0 branches:
		dist/bind/bin/named/update.c

	To update from CVS, re-build, and re-install bind:

		# cd src
		# cvs update -r <branch_name> -d -P dist/bind/bin/named/update.c
		# cd usr.sbin/bind/named
		# make USETOOLS=no cleandir dependall
		# make USETOOLS=no install

* NetBSD 4.*:

	Systems running NetBSD 4.* sources dated from before
	2009-07-28 22:19 UTC should be upgraded from NetBSD 4.* sources
	dated 2009-07-28 22:19 UTC or later.

	The following files/directories need to be updated from the
	netbsd-4 or netbsd-4-0 branches:
		dist/bind/bin/named/update.c

	To update from CVS, re-build, and re-install bind:

		# cd src
		# cvs update -r <branch_name> -d -P dist/bind/bin/named/update.c
		# cd usr.sbin/bind/named
		# make USETOOLS=no cleandir dependall
		# make USETOOLS=no install


Thanks To
=========

Matthias Urlichs for finding and reporting this bug and Christos Zoulas
for fixing it in NetBSD.


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

	2009-07-29	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-SA2009-013.txt.asc

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

Copyright 2009, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2009-013.txt,v 1.1 2009/07/29 06:54:37 tonnerre Exp $

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