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		 NetBSD Security Advisory 2009-011
		 =================================

Topic:		ISC DHCP server Denial of Service vulnerability

Version:	NetBSD-current:		affected prior to 2009-07-16
		NetBSD 5.0:		affected
		NetBSD 4.0.*:		affected
		NetBSD 4.0:		affected
		pkgsrc:			isc-dhcpd package prior to 3.1.1p1

Severity:	Denial of Service

Fixed:		NetBSD-current:		Jul 16, 2009
		NetBSD-5-0 branch:	Jul 17, 2009
		NetBSD-5 branch:	Jul 17, 2009
		NetBSD-4-0 branch:	Jul 17, 2009
		NetBSD-4 branch:	Jul 17, 2009
		pkgsrc 2009Q2:		isc-dhcpd-3.1.1p1 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
========

A reference counting error in dhcpd allows a remote attacker to cause
a daemon crash by submitting requests with the same client ID on
different interfaces served by the same daemon.

This vulnerability has been assigned CVE-2009-1892.


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

A reference counting error in dhcpd allows a remote attacker to cause
a daemon crash by submitting requests with the same client ID on
different interfaces served by the same daemon.

This requires that client ID based configurations are mixed in the
configuration file with hardware address based configurations.


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

In order to fix the vulnerability on your local machine, either
make sure that only client-id based statements or hardware ethernet
statements are used, or upgrade to a non-vulnerable version of
dhcpd.

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

* NetBSD-current:

	Systems running NetBSD-current dated from before 2009-07-16
	should be upgraded to NetBSD-current dated 2009-07-17 or later.

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

	To update from CVS, re-build, and re-install lorem:
		# cd src
		# cvs update -d -P dist/dhcp/server
		# cd usr.sbin/dhcp
		# make USETOOLS=no cleandir dependall
		# cd server
		# make USETOOLS=no install

* NetBSD 5.*:

	Systems running NetBSD 5.* sources dated from before
	2009-07-17 should be upgraded from NetBSD 5.* sources dated
	2009-07-18 or later.

	The following files/directories need to be updated from the
	netbsd-5 or netbsd-5-0 branches:
		dist/dhcp/server

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

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

* NetBSD 4.*:

	Systems running NetBSD 4.* sources dated from before
	2009-07-17 should be upgraded from NetBSD 4.* sources dated
	2009-07-18 or later.

	The following files/directories need to be updated from the
	netbsd-4 or netbsd-4-0 branches:
		dist/dhcp/server

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

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


Thanks To
=========

Christoph Biedl for discovering and reporting the issue, and Florian
Weimer for the fix.


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

	2009-07-28	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-SA2009-011.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-SA2009-011.txt,v 1.1 2009/07/28 18:29:29 tonnerre Exp $

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