Date: Wed, 17 Dec 2003 13:56:31 -0500
From: NetBSD Security Officer <security-officer@NetBSD.org.>
To: [email protected]Subject: NetBSD Security Advisory 2003-018: DNS negative cache poisoning
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NetBSD Security Advisory 2003-018
Topic: DNS negative cache poisoning
Version: NetBSD-current: source prior to Nov 27, 2003
NetBSD 1.6.2_RC3: not affected
NetBSD 1.6.2_RC2: affected
NetBSD 1.6.2_RC1: affected
NetBSD 1.6: affected
NetBSD-1.5.3: affected
NetBSD-1.5.2: affected
NetBSD-1.5.1: affected
NetBSD-1.5: affected
pkgsrc: bind8 packages prior to 8.4.3
bind9 packages unaffected
Severity: Denial of service resolving DNS entries
Fixed: NetBSD-current: Nov 27, 2003
NetBSD-1.6 branch: Nov 28, 2003 (1.6.2 will include the fix)
(1.6.2_RC3 includes the fix)
NetBSD-1.5 branch: Nov 28, 2003
pkgsrc bind8: bind8-8.4.3 will correct this issue
Abstract
========
If an attacker can trigger your DNS server to do a lookup via a server
he controls, the malign server can inject authoritative negative
responses with long time to live values. Your DNS server will cache the
lie that the relevant resource records do not exist.
Technical Details
=================
- From CERT VU#734644:
http://www.kb.cert.org/vuls/id/734644
Several versions of the BIND 8 name server are vulnerable to cache
poisoning via negative responses. To exploit this vulnerability, an
attacker must configure a name server to return authoritative negative
responses for a given target domain. Then, the attacker must convince a
victim user to query the attacker's maliciously configured name server.
When the attacker's name server receives the query, it will reply with
an authoritative negative response containing a large TTL (time-to-live)
value. If the victim's site runs a vulnerable version of BIND 8, it will
cache the negative response and render the target domain unreachable
until the TTL expires.
NOTE: While ISC released two patch versions for this vulunerability
(8.3.7 and 8.4.3) a query-storm bug has been discovered in the 8.4.3
version. The 8.3.7 version which currently ships as part of NetBSD does
not have this bug. ISC recommends against moving production servers to
8.4.3
Solutions and Workarounds
If you are not running named(8), your system is not affected.
BIND 9 is not affected by these vulnerabilities. Upgrading to BIND 9
is recommended. BIND 9 is available in the NetBSD Pkgsrc Collection
(pkgsrc/net/bind9). Configuration files differ between BIND 8 and
9. Plan such a migration appropriately.
The following instructions describe how to upgrade your named
binaries by updating your source tree and rebuilding and
installing a new version of named.
Be sure to restart running instance of named(8) after installation.
* NetBSD-current:
Systems running NetBSD-current dated from before 2002-11-27
should be upgraded to NetBSD-current dated 2002-11-27 or later.
The following directories need to be updated from the
netbsd-current CVS branch (aka HEAD):
dist/bind
usr.sbin/bind
To update from CVS, re-build, and re-install named:
# cd src
# cvs update -d -P dist/bind usr.sbin/bind
# cd usr.sbin/bind
# make USETOOLS=no cleandir dependall
# make USETOOLS=no install
* NetBSD 1.6, 1.6.1:
The binary distributions of NetBSD 1.6 and 1.6.1 are vulnerable.
Systems running NetBSD 1.6 sources dated from before 2002-11-28
should be upgraded from NetBSD 1.6 sources dated 2002-11-28 or
later.
NetBSD 1.6.2 will include the fix.
* Binary patch:
To apply the binary patch, perform the following steps,
replacing ARCH with the NetBSD architecture you are running
(i.e. i386):
ftp://ftp.netbsd.org/pub/NetBSD/security/patches/SA2003-018-bind/netbsd-1-6/ARCH-bind.tgz
cd / && tar xzvpf /path/to/ARCH-bind.tgz
The tar file will extract a new copy of:
/usr/sbin/named
Then restart named.
* Updating from sources:
The following directories need to be updated from the
netbsd-1-6 CVS branch:
dist/bind
usr.sbin/bind
To update from CVS, re-build, and re-install named:
# cd src
# cvs update -d -P -r netbsd-1-6 dist/bind usr.sbin/bind
# cd usr.sbin/bind
# make USETOOLS=no cleandir dependall
# make USETOOLS=no install
* NetBSD 1.5, 1.5.1, 1.5.2, 1.5.3:
The binary distributions of NetBSD 1.5 to 1.5.3 are vulnerable.
Systems running NetBSD 1.5, 1.5.1, 1.5.2 or 1.5.3 sources dated
from before 2002-11-28 should be upgraded to NetBSD 1.5 sources
dated 2002-11-28 or later.
The following directories need to be updated from the
netbsd-1-5 CVS branch:
dist/bind
usr.sbin/bind
To update from CVS, re-build, and re-install named:
# cd src
# cvs update -d -P -r netbsd-1-5 dist/bind usr.sbin/bind
# cd usr.sbin/bind
# make cleandir dependall
# make install
* pkgsrc
bind8 versions prior to 8.3.7 and 8.4.3 are vulnerable. ISC has
not released 8.4.4. Upgrade to bind-8.4.4 or later when
available, or upgrade to bind9 (if appropriate for your
requirements)
Thanks To
=========
CERT
Revision History
================
2003-12-16 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
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2003-018.txt.asc
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/.
Copyright 2003, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
$NetBSD: NetBSD-SA2003-018.txt,v 1.10 2003/12/17 03:08:24 david Exp $
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