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IBM SECURITY ADVISORY

First Issued: Thu May 20 16:44:30 CDT 2010

The most recent version of this document is available here:

http://aix.software.ibm.com/aix/efixes/security/pcnfsd_advisory.asc

VULNERABILITY SUMMARY

VULNERABILITY: AIX rpc.pcnfsd integer overflow vulnerability

PLATFORMS: AIX 5.3, 6.1, and earlier releases
VIOS 1.5, 2.1, and earlier releases

SOLUTION: Apply the fix or workaround as described below.

THREAT: This can be exploited to cause an integer overflow via a
specially crafted RPC request. Successful exploitation of
this issue could allow the attacker to execute arbitrary
code on an affected system.

CERT VU Number: N/A
CVE Number: CVE-2010-1039

Reboot required? NO
Workarounds? YES
Protected by FPM? NO
Protected by SED? NO

DETAILED INFORMATION

I. DESCRIPTION (from IPS Research Center)

"An integer overflow vulnerability was reported in the rpc.pcnfsd
service within the several systems. The rpc.pcnfsd daemon handles
requests from PC-NFS clients for authentication services on
remote machines. These services include authentication for
mounting and for print spooling. The vulnerability is triggered
when parsing crafted RPC requests. A remote attacker can leverage
this vulnerability by sending a crafted RPC message to the target
host, to potentially inject and execute arbitrary code."

Please see the following for more information:

http://www.checkpoint.com/defense/advisories/public/2010/cpai-13-May.html

II. PLATFORM VULNERABILITY ASSESSMENT

Note: To use the following commands on VIOS you must first
execute:

oem_setup_env

To determine if your system is vulnerable, execute the following
command:

lslpp -L bos.net.nfs.client

The following fileset levels are vulnerable:

AIX Fileset Lower Level Upper Level
------------------------------------------------
bos.net.nfs.client 5.3.9.0 5.3.9.7
bos.net.nfs.client 5.3.10.0 5.3.10.4
bos.net.nfs.client 5.3.11.0 5.3.11.4
bos.net.nfs.client 5.3.12.0 5.3.12.1
bos.net.nfs.client 6.1.2.0 6.1.2.7
bos.net.nfs.client 6.1.3.0 6.1.3.4
bos.net.nfs.client 6.1.4.0 6.1.4.4
bos.net.nfs.client 6.1.5.0 6.1.5.1

III. SOLUTION

A. FIXES

Fixes are now available. The fixes can be downloaded from:

http://aix.software.ibm.com/aix/efixes/security/pcnfsd_fix.tar

The links above are to a tar file containing this signed
advisory, fix packages, and PGP signatures for each package.

AIX Level VIOS Level Fix
-------------------------------------------------------------------
5.3.9 1.5.2 IZ73874_09.100520.epkg.Z
5.3.10 IZ73757_10.100520.epkg.Z
5.3.11 IZ73681_11.100520.epkg.Z
5.3.12 IZ73590_12.100520.epkg.Z
6.1.2 2.1.0 IZ75465_02.100520.epkg.Z
6.1.3 2.1.1 IZ75440_03.100520.epkg.Z
6.1.4 2.1.2 IZ75369_04.100520.epkg.Z
6.1.5 2.1.3 IZ73599_05.100520.epkg.Z

To extract the fixes from the tar file:

tar xvf pcnfsd_fix.tar
cd pcnfsd_fix

Verify you have retrieved the fixes intact:

The checksums below were generated using the "csum -h SHA1"
(sha1sum) commands and are as follows:

csum -h SHA1 (sha1sum) filename
------------------------------------------------------------------
e674c6f69fe943f54a7a93f6786264344864063c IZ73590_12.100520.epkg.Z
620f8b39a994dd5ccd496d037c56786184a17dd4 IZ73599_05.100520.epkg.Z
b2c42ca760d166ebe26f8865a7d04e03ddf00a5d IZ73681_11.100520.epkg.Z
28e874371b5fb111040acd5102a5e8dd0398bdfe IZ73757_10.100520.epkg.Z
9ac461a3e65b970a76bb985b30838126a9e9aaa4 IZ73874_09.100520.epkg.Z
0d568287bc7f64fe49fbc105d6b17084dad1cbb2 IZ75369_04.100520.epkg.Z
1caee8275ef5cda18fb271cc2f7ad7e1ce2af1c1 IZ75440_03.100520.epkg.Z
53b6e98a1bc1d23c611f88f446c1141b7dee87fc IZ75465_02.100520.epkg.Z

To verify the sums, use the text of this advisory as input to
csum or sha1sum. For example:

csum -h SHA1 -i Advisory.asc
sha1sum -c Advisory.asc

These sums should match exactly. The PGP signatures in the tar
file and on this advisory can also be used to verify the
integrity of the fixes. If the sums or signatures cannot be
confirmed, contact IBM AIX Security and describe the
discrepancy at the following address:

security-alert@austin.ibm.com

B. FIX INSTALLATION

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

Fix management documentation can be found at:

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

To preview fix installation:

emgr -e fix_name -p # where fix_name is the name of the
# fix being previewed.

To install fix package:

emgr -e fix_name -X # where fix_name is the name of the
# fix being installed.

IMPORTANT: The fix will not take affect until any running rpc.pcnfsd
servers have been stopped and restarted with the following
commands:

     Stop:
     1. comment out pcnfsd entry in /etc/inetd.conf
     2. kill rpc.pcnfsd
     3. refresh inetd

     apply fix

     Start:
     1. uncomment pcnfsd entry in /etc/inetd.conf
     2. refresh inetd

C. APARS

IBM has assigned the following APARs to this problem:

AIX Level APAR number Service pack date
--------------------------------------------------------
5.3.9 IZ73874 9/22/10 sp8
5.3.10 IZ73757 9/22/10 sp5
5.3.11 IZ73681 9/22/10 sp5
5.3.12 IZ73590 9/22/10 sp2
6.1.2 IZ75465 6/16/10 sp9
6.1.3 IZ75440 6/16/10 sp6
6.1.4 IZ75369 6/16/10 sp6
6.1.5 IZ73599 8/25/10 sp2

Subscribe to the APARs here:

http://www.ibm.com/support/docview.wss?uid=isg1IZ73874
http://www.ibm.com/support/docview.wss?uid=isg1IZ73757
http://www.ibm.com/support/docview.wss?uid=isg1IZ73681
http://www.ibm.com/support/docview.wss?uid=isg1IZ73590
http://www.ibm.com/support/docview.wss?uid=isg1IZ75465
http://www.ibm.com/support/docview.wss?uid=isg1IZ75440
http://www.ibm.com/support/docview.wss?uid=isg1IZ75369
http://www.ibm.com/support/docview.wss?uid=isg1IZ73599

By subscribing, you will receive periodic email alerting you
to the status of the APAR, and a link to download the service
pack when it becomes available.

IV. WORKAROUND

Don't run rpc.pcnfsd. Comment the entry for rpc.pcnfsd from
/etc/inetd.conf and refresh the instance of inetd. This can
be done by running the following command.

/usr/bin/refresh -s inetd

VI. CONTACT INFORMATION

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

http://www.ibm.com/systems/support

and click on the "My notifications" link.

To view previously issued advisories, 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 obtain the PGP public key that can be used to communicate
securely with the AIX Security Team you can either:

A. Send an email with "get key" in the subject line to:

security-alert@austin.ibm.com

B. Download the key from our web page:

http://www.ibm.com/systems/resources/systems_p_os_aix_security_pgpkey.txt

C. Download the key from a PGP Public Key Server. The key ID is:

0x28BFAA12

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.

VII. ACKNOWLEDGMENTS

This vulnerability was discovered and exploited by Rodrigo Rubira Branco.

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