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AUSCERT External Security Bulletin Redistribution
ESB-2007.0154 -- [NetBSD]
BIND multiple denial of service vulnerabilities
9 March 2007
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AusCERT Security Bulletin Summary
---------------------------------
Product: BIND
Publisher: NetBSD
Operating System: NetBSD
Impact: Denial of Service
Access: Remote/Unauthenticated
CVE Names: CVE-2007-0494 CVE-2007-0493
Ref: ESB-2007.0050
Original Bulletin:
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2007-003.txt.asc
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NetBSD Security Advisory 2007-003
=================================
Topic: BIND multiple denial of service vulnerabilities
Version: NetBSD-current: source prior to January 27, 2007
NetBSD 4.0_BETA2: affected
NetBSD 3.1: affected
NetBSD 3.0.*: affected
NetBSD 3.0: affected
NetBSD 2.1: not affected
NetBSD 2.0.*: not affected
NetBSD 2.0: not affected
pkgsrc: bind-9.3.2 and earlier
Severity: Denial of service
Fixed: NetBSD-current: January 27, 2007
NetBSD-4 branch: March 04, 2007
NetBSD-3-1 branch: March 04, 2007
NetBSD-3-0 branch: March 04, 2007
NetBSD-3 branch: March 04, 2007
pkgsrc: bind-9.3.4 corrects the issue
Abstract
========
Two denial of service vulnerabilities have been reported in bind which
can cause the name server daemon to crash. The vulnerabilities relate
to the processing of type * (ANY) queries and recursive queries.
The ANY query processing issue has been assigned CVE reference CVE-2007-0493.
The recursive query issue has been assigned CVE reference CVE-2007-0494.
Technical Details
=================
Issue #1: * (ANY) query processing
This issue is relating to the way in which the server processes
a type * (ANY) query. In order for this attack to be successful
the query must return multiple RRsets in the answer section. In
addition to this the server must be configured with dnssec
validation enabled.
Issue #2: Recursive query handling
This issue is relating to the way in which the server processes
recursive queries. The request, in this case, can cause named to
read a freed fetch context. The server needs to be enabled to
receive recursive queries in order for this attack to be successful.
Solutions and Workarounds
=========================
If you have not enabled dnssec validation in your name server then you
are not vulnerable to the * (ANY) denial of service attack. Both
vulnerabilities can be mitigated by limiting who can perform specific
queries against the name server.
In particular, it is recommended practice, regardless of this
vulnerability, to accept recursive queries only from local clients who
would be expected to query this nameserver directly, not from unknown
Internet sources. The 'allow-recursion' directive in the options
section of named.conf should be configured with an appropriate address
list, as in the following simple example:
options {
directory "/etc/namedb";
allow-recursion { 1.2.3.4/24; 127.0.0.1/32; ::1; };
};
It is recommended that NetBSD users of vulnerable versions update
their binaries.
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 2007-01-27
should be upgraded to NetBSD-current dated 2007-01-28 or later.
Due to the amount of changes introduced in the BIND upgrade
in CVS HEAD it is recommended that users of NetBSD-current
perform a full system upgrade to sources dated after 2007-01-28.
For more information on how to do this, see:
http://www.netbsd.org/Documentation/current/
* NetBSD 3.*:
Systems running NetBSD 3.* sources dated from before
2007-03-04 should be upgraded from NetBSD 3.* sources dated
2007-03-05 or later.
The following files need to be updated from the
netbsd-3, netbsd-3-0 or netbsd-3-1 branch:
dist/bind/lib/dns/resolver.c
dist/bind/lib/dns/validator.c
dist/bind/lib/dns/include/dns/validator.h
dist/bind/version
To update from CVS, re-build, and re-install bind:
# cd src
# cvs update -r <branch_name> dist/bind/lib/dns/resolver.c
# cvs update -r <branch_name> dist/bind/lib/dns/validator.c
# cvs update -r <branch_name> \
dist/bind/lib/dns/include/dns/validator.h
# cvs update -r <branch_name> dist/bind/version
# cd usr.sbin/bind
# make USETOOLS=no cleandir dependall
# make USETOOLS=no install
Thanks To
=========
The Internet Software Consortium is credited with the discovery and
correction of both issues.
Revision History
================
2007-03-08 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-SA2007-003.txt.asc
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/.
Copyright 2007, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
$NetBSD: NetBSD-SA2007-003.txt,v 1.2 2007/03/08 19:32:38 adrianp Exp $
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