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NetBSD Security Advisory 2012-004: BIND resolver DoS when using DNSSEC Validation

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                NetBSD Security Advisory 2012-004

Topic:          BIND resolver DoS when using DNSSEC Validation

Version:        NetBSD-current:         affected prior to 20120724
                NetBSD 6 BETA:          affected prior to 20120725
                NetBSD 5.1:             affected prior to 20120725
                NetBSD 5.0:             affected prior to 20120725
                NetBSD 4.0.*:           affected prior to 20120724
                NetBSD 4.0:             affected prior to 20120724
                pkgsrc:                 net/bind96, net/bind97,
                                        net/bind98, net/bind99
                                        packages prior to 20120724

Severity:       Denial of Service

Fixed:          NetBSD-current:         Jul 24th, 2012
                NetBSD-5-1 branch:      Jul 25th, 2012
                NetBSD-5-0 branch:      Jul 25th, 2012
                NetBSD-5 branch:        Jul 25th, 2012
                NetBSD-4-0 branch:      Jul 24th, 2012
                NetBSD-4 branch:        Jul 24th, 2012
                pkgsrc net/bind96:      bind-
                pkgsrc net/bind97:      bind-9.7.6pl2
                pkgsrc net/bind98:      bind-9.8.3pl2nb1
                pkgsrc net/bind99:      bind-9.9.1pl2

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


High numbers of queries with DNSSEC validation enabled can cause a
crash with an assertion failure in named, caused by using a "bad cache"
data structure before it has been initialized.

This vulnerability has been assigned CVE-2012-3817.

Technical Details

BIND 9 stores a cache of query names that are known to be failing
due to misconfigured name servers or a broken chain of trust.
Under high query loads when DNSSEC validation is active, it is
possible for a condition to arise in which data from this cache of
failing queries could be used before it was fully initialized,
triggering an assertion failure.

DNSSEC validation is enabled by default in NetBSD 5 and newer.

Solutions and Workarounds

We suggest fixing this vulnerability by using the current equivalent
net/bind9* 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 from past
the fix date).

In order to apply this fix from source code, you will need to update the
directory src/dist/bind under NetBSD 4.* and 5.*, or the directory
src/external/bsd/bind/dist under NetBSD 6.0_BETA and later, to a version
from a date later than what is mentioned in the "Fixed" section.

Thanks To

Thanks to the Internet Systems Consortium for reporting this
vulnerability and providing fixed versions.

Revision History

        2012-07-25      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

Information about NetBSD and NetBSD security can be found at and .

Copyright 2012, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2012-004.txt,v 1.1 2012/07/25 15:53:18 tonnerre Exp $

Version: GnuPG v1.4.12 (GNU/Linux)


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