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FreeBSD-SA-15:05.bind                                       Security Advisory
                                                          The FreeBSD Project

Topic:          BIND remote denial of service vulnerability

Category:       contrib
Module:         bind
Announced:      2015-02-25
Credits:        ISC
Affects:        FreeBSD 8.x and FreeBSD 9.x.
Corrected:      2015-02-18 22:20:19 UTC (stable/9, 9.3-STABLE)
                2015-02-25 05:56:54 UTC (releng/9.3, 9.3-RELEASE-p10)
                2015-02-18 22:29:52 UTC (stable/8, 8.4-STABLE)
                2015-02-25 05:56:54 UTC (releng/8.4, 8.4-RELEASE-p24)
CVE Name:       CVE-2015-1349

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.

I.   Background

BIND 9 is an implementation of the Domain Name System (DNS) protocols.
The named(8) daemon is an Internet Domain Name Server.

II.  Problem Description

BIND servers which are configured to perform DNSSEC validation and which
are using managed keys (which occurs implicitly when using
"dnssec-validation auto;" or "dnssec-lookaside auto;") may exhibit
unpredictable behavior due to the use of an improperly initialized
variable.

III. Impact

A remote attacker can trigger a crash of a name server that is configured
to use managed keys under specific and limited circumstances.  However,
the complexity of the attack is very high unless the attacker has a
specific network relationship to the BIND server which is targeted.

IV.  Workaround

Only systems that runs BIND, including recursive resolvers and authoritative
servers that performs DNSSEC validation and using managed-keys are affected.

This issue can be worked around by not using "auto" for the dnssec-validation
or dnssec-lookaside options and do not configure a managed-keys statement.
Note that in order to do DNSSEC validation with this workaround one would
have to configure an explicit trusted-keys statement with the appropriate
keys.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.

2) To update your vulnerable system via a binary patch:

Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install

3) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch https://security.FreeBSD.org/patches/SA-15:05/bind.patch
# fetch https://security.FreeBSD.org/patches/SA-15:05/bind.patch.asc
# gpg --verify bind.patch.asc

b) Apply the patch.  Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

c) Recompile the operating system using buildworld and installworld as
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.

Restart the applicable daemons, or reboot the system.

VI.  Correction details

The following list contains the correction revision numbers for each
affected branch.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/8/                                                         r278973
releng/8.4/                                                       r279265
stable/9/                                                         r278972
releng/9.3/                                                       r279265
- -------------------------------------------------------------------------

To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:

# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base

Or visit the following URL, replacing NNNNNN with the revision number:

<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>

VII. References

<URL:https://kb.isc.org/article/AA-01235>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-1349>

The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-15:05.bind.asc>
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