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IBM SECURITY ADVISORY
First Issued: Tue May 29 09:56:55 CDT 2007

==========================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:      A vulnerability in the BIND could allow a 
                    remote attacker to cause a denial of service.

PLATFORMS:          AIX 5.2, 5.3

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

THREAT:             A remote attacker may cause a denial of service.

CERT VU Number:     n/a
CVE Number:         CVE-2007-0494
==========================================================================
                           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. 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. For this vulnerability to be exploited, two conditions must be met.
First, BIND must be configured to use DNSSEC validation. Second, BIND's
response to type ANY queries must contain multiple RRsets.

The following table shows the versions of bos.net.tcp.client which are
affected by this vulnerability:

AIX Release          Lower         Upper
                     Level         Level
============================================
AIX 5.2              5.2.0.0       5.2.0.105
AIX 5.3              5.3.0.0       5.3.0.60


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

A remote attacker may be able to cause the name server daemon to crash
resulting in a denial of service.

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

A. APARs

IBM provides the following fixes:

      APAR number for AIX 5200-10: IY98546  (available approx. 06/01/07)
      APAR number for AIX 5300-06: IY98417  (available approx. 06/01/07)

Customers should ensure that APARs IY98546 and IY98417 are installed on
5200-10 and 5300-06 systems respectively. If these APARs are not installed,
they should be downloaded from Fix Central. These technology levels and
APARs will be made available concurrently.

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

B. Interim Fix

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

    ftp://aix.software.ibm.com/aix/efixes/security/binddnssec_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 checksums below were generated using the "sum" and "md5sum" commands
and are as follows:

Filename                   sum           md5
=========================================================================
IY98546_07.052307.epkg.Z   62525  3034   2116a66217562e2c2a47836be790817e
IY98546_08.052307.epkg.Z   32994  3035   ff8b9a94b7bbfc431d71a752e75e5c7c
IY98546_09.052307.epkg.Z   22652  3034   08a44db305322e4878b03cae31a6532d
IY98417_03.052307.epkg.Z   28058  2966   037ae36cd0d9b8a58f42498edb7db34c
IY98417_04.052307.epkg.Z   44671  2965   dbd1c88cdb500df50d70eaa3e065d9f1
IY98417_05.052307.epkg.Z   52995  2959   948504470b81e8f0da5f1fb1851fd240

See the table below to determine which AIX Technology Level a given interim
fix maps to.

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 levels show are for bos.net.tcp.client.

Interim                    Fileset Level     Fileset Level   AIX
Fix                        (lower level)     (upper level)   Level
=====================================================================
IY98546_07.052307.epkg.Z   5.2.0.77          5.2.0.77        5200-07
IY98546_08.052307.epkg.Z   5.2.0.88          5.2.0.88        5200-08
IY98546_09.052307.epkg.Z   5.2.0.99          5.2.0.99        5200-09
IY98417_03.052307.epkg.Z   5.3.0.32          5.3.0.32        5300-03
IY98417_04.052307.epkg.Z   5.3.0.44          5.3.0.44        5200-04
IY98417_05.052307.epkg.Z   5.3.0.54          5.3.0.54        5300-05

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

Customers may contact IBM support if any issues arise with these interim
fixes.

Interim Installation Instructions:
+---------------------------------
These packages use the new Interim Fix Management Solution to install and
manage interim fixes. More information can be found at:

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

To preview an epkg interim fix installation execute the following command:

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

To install an epkg interim fix package, execute the following command:

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

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

C. Workaround

Disable the daemons if they are not being used.

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 0x092546E5.

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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