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IBM SECURITY ADVISORY


First Issued: Wed Sep  6 12:09:29 CDT 2006
==========================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:      Potential denial of service vulnerability in
                    BIND 9.2.1.

PLATFORMS:          BIND 9.2.1 on AIX 5.2 and 5.3.

SOLUTION:           Apply the APAR, interim fix or workaround as
                    described below.

THREAT:             Potential denial of service vulnerability in
                    BIND 9.2.1.

CERT VU Number:     VU#697164
CVE Number:         CVE-2006-4096
=========================================================================
                           DETAILED INFORMATION


I.  Description
===============

Berkeley Internet Name Domain 9 (BIND 9) is a Domain Name System (DNS)
distribution from the Internet Systems Consortium (ISC) and it is included
with AIX 5.2 and 5.3. At this time, all versions of AIX 5.2 and 5.3 include
BIND 9.2.1. The ISC has issued a patch for a security vulnerability in some
versions of BIND 9 that can be exploited by a remote attacker to cause a
denial of service. There is no known exploit vector for this issue in BIND
9.2.1. Nonetheless, IBM is making fixes available that remove this
potential issue from BIND 9.2.1.

CERT Vulnerability Notes VU#697164 and VU#915404 were released
concurrently. BIND 9.2.1 is not affected by VU#915404.


II. Impact
==========

A remote user may cause a denial of service. At this time, there is no
known way for an attacker to exploit this issue.


III.  Solutions
===============

A. APARs

IBM provides the following fixes:

      APAR number for AIX 5.2.0:  IY89178 (available approx. 10/18/06)
      APAR number for AIX 5.3.0:  IY89169 (available approx. 10/04/06)

NOTE: Affected customers are urged to upgrade to the latest applicable
Technology Level.

B. Interim Fixes

Interim fixes are available. The ifixes can be downloaded via ftp from:

    ftp://aix.software.ibm.com/aix/efixes/security/bind9_ifix.tar.Z

This is a compressed tarball containing this advisory, interim fix packages
and cleartext PGP signatures for each package.


Verify you have retrieved the fixes intact:
+------------------------------------------
The interim fixes below are named by using the APAR corresponding to the
release that the fix applies to. The APAR is followed by an underscore and
the Technology Level for the particular AIX release that a fix applies to.

The checksums below were generated using the "sum" and "md5sum" commands
and are as follows:


Filename                   sum           md5
=========================================================================
IY89178_07.060905.epkg.Z   58539  3033   eb47c83e55148b1ca56db8185d1d209e
IY89178_08.060905.epkg.Z   57923  3033   966b9b799c750114d5d991ed4657354d
IY89178_09.060905.epkg.Z   29260  3032   76729cef9c209228118c5f69caff2ccf
IY89169_03.060905.epkg.Z   32955  2964   e7be01b53eecf1ff4938262861798e85
IY89169_04.060905.epkg.Z   51411  2963   af54f94028504d70646cb4ca0c40b112
IY89169_05.060905.epkg.Z   50142  2961   90290712ffc95778cf6a0a367a82dc62

These sums should match exactly. The PGP signatures in the compressed
tarball and on this advisory can also be used to verify the integrity of
the various files they correspond to. If the sums or signatures cannot be
confirmed, double check the command results and the download site address.
If those are OK, contact IBM AIX Security at security-alert@austin.ibm.com
and describe the discrepancy.

The interim fixes include prerequisite checking. This will ensure the
correct mapping between the interim fixes and AIX Technology Levels. The
following table shows the prerequisite fileset levels required for the
fixes above. The fileset levels listed are for bos.net.tcp.client.

Interim                    Fileset Level     Fileset Level
Fix                        (lower limit)     (upper limit)
===================================================================
IY89178_07.060905.epkg.Z   5.2.0.77          5.2.0.77
IY89178_08.060905.epkg.Z   5.2.0.88          5.2.0.88
IY89178_09.060905.epkg.Z   5.2.0.95          5.2.0.96
IY89169_03.060905.epkg.Z   5.3.0.32          5.3.0.32
IY89169_04.060905.epkg.Z   5.3.0.44          5.3.0.44
IY89169_05.060905.epkg.Z   5.3.0.50          5.3.0.51


IMPORTANT: If possible, it is recommended that a mksysb backup of the
system is created. Verify it is both bootable, and readable before
proceeding.

These interim fixes have not been fully regression tested; thus, IBM does
not warrant the fully correct functioning of the interim fix. Customers
install the interim fix and operate the modified version of AIX at their
own risk.


Interim Installation Instructions:
+---------------------------------

Before installing the interim fix, stop named9. This can be done by
executing the following command:

# stopsrc -s named

These packages use the new Interim Fix Management Solution to install and
manage ifixes. More information can be found at:

     http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html

To preview an epkg ifix installation execute the following command:

# emgr -e ipkg_name -p       # where ipkg_name is the name of the
                             # ifix package being previewed.

To install an epkg ifix package, execute the following command:

# emgr -e ipkg_name -X       # where ipkg_name is the name of the
                             # ifix package being installed.

The "X" flag will expand any filesystems if required.

After installing the interim, restart named9. This can be done by executing
the following command:

# startsrc -s named

C. Workaround

Limit the hosts that can do recursive queries through the server. For more
information see:

AIX 5.2:     http://publib16.boulder.ibm.com/doc_link/en_US/a_doc_lib/
             files/aixfiles/named.conf.htm

AIX 5.3:     http://publib.boulder.ibm.com/infocenter/pseries/v5r3/
             topic/com.ibm.aix.files/doc/aixfiles/named.conf.htm

Please note that the URLs above are wrapped.


IV. Obtaining Fixes
===================

AIX Version 5 APARs can be downloaded from:

     http://www.ibm.com/servers/eserver/support/unixservers/aixfixes.html

Security related Interim Fixes can be downloaded from:

     ftp://aix.software.ibm.com/aix/efixes/security


V.  Contact Information
=======================

If you would like to receive AIX Security Advisories via email, please
visit:

     http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd

Comments regarding the content of this announcement can be directed to:

     security-alert@austin.ibm.com

To request the PGP public key that can be used to communicate securely
with the AIX Security Team send email to security-alert@austin.ibm.com
with a subject of "get key". The key can also be downloaded from a PGP
Public Key Server. The key id is 0x1B14F299.

Please contact your local IBM AIX support center for any assistance.

eServer is a trademark of International Business Machines Corporation.
IBM, AIX and pSeries are registered trademarks of International Business
Machines Corporation. All other trademarks are property of their respective
holders.
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