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Re: iDEFENSE Security Advisory 02.10.05: IBM AIX netpmon Local Buffer Overflow Vulnerability



The IBM Advisory:


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IBM SECURITY ADVISORY
First Issued: Wed Feb  9 15:16:37 CST 2005

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

VULNERABILITY:      A buffer overflow in netpmon may allow a local user
                    in the system group to gain root privileges.

PLATFORMS:          AIX 5.1, 5.2 and 5.3.

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

THREAT:             A local user in the system group may gain root
                    privileges.

CERT VU Number:     N/A
CVE Number:         N/A
=========================================================================
                           DETAILED INFORMATION


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

A buffer overflow vulnerability was discovered in the netpmon command.
This command monitors activity and reports statistics on network I/O and
network-related CPU usage. A user in the system group may exploit this
vulnerability to gain root privileges.

The command affected by this issue ships as part of the bos.perf.tools
fileset. To determine if this fileset is installed, execute the following
command:

# lslpp -L bos.perf.tools

If the fileset is installed it will be listed along with its version
information, state, type and a description.


II. Impact
==========
A local user in the system group may gain root privileges.


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

A. Official Fix

IBM provides the following fixes:

      APAR number for AIX 5.1.0: IY67807  (available approx. 03/23/05)
      APAR number for AIX 5.2.0: IY67136  (available approx. 04/15/05)
      APAR number for AIX 5.3.0: IY67124  (available approx. 04/15/05)

NOTE: Affected customers are urged to upgrade to 5.1.0, 5.2.0 or 5.3.0 at
the latest maintenance level.

B. Emergency Fix

Efixes are available for AIX 5.1.0, 5.2.0 and 5.3.0. The efixes can be
downloaded via ftp from:

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

netpmon_efix.tar.Z is a compressed tarball containing this advisory, three
efix packages cleartext PGP signatures for each efix package.


Verify you have retrieved the efixes intact:
- --------------------------------------------
The checksums below were generated using the "sum" and "md5sum" commands
and are as follows:

Filename                 sum         md5
=====================================================================
IY67807.050209.epkg.Z   27708    70  3c2ffeeca5c573862131b5680df7098b
IY67136.050209.epkg.Z   32162    51  aa6d54e0e2dfb4d5c6183050f97b7036
IY67124.050209.epkg.Z   58778    53  39d78095acf72a77630d3a2022155edb


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@xxxxxxxxxxxxxx
and describe the discrepancy.

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

Efix Installation Instructions:
- -------------------------------
These packages use the new Emergency Fix Management Solution to install
and manage efixes. More information can be found at:

     http://techsupport.services.ibm.com/server/aix.efixmgmt

To preview an epkg efix installation execute the following command:

# emgr -e epkg_name -p       # where epkg_name is the name of the
                             # efix package being previewed.

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

# emgr -e epkg_name -X       # where epkg_name is the name of the
                             # efix package being installed.

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

C. Workaround

Setting the file mode bits to 500 will allow only the root user to execute
the netpmon command. This can be done by executing the following command
as root:

# chmod 500 /usr/bin/netpmon 

Verify that the file mode bits have been changed to 500:

# ls -la /usr/bin/netpmon
- -r-x------  1 root system 83454 2003-04-09 18:48 /usr/bin/netpmon


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

AIX Version 5 APARs can be downloaded from:

     http://www-1.ibm.com/servers/eserver/support/pseries/aixfixes.html

Security related Emergency Fixes can be downloaded from:

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


V.  Acknowledgments
====================
This vulnerability was reported by iDEFENSE.


VI.  Contact Information
========================

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

     https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs

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

     security-alert@xxxxxxxxxxxxxx

To request the PGP public key that can be used to communicate securely
with the AIX Security Team send email to security-alert@xxxxxxxxxxxxxx
with a subject of "get key". The key can also be downloaded from a PGP
Public Key Server. The key id is 0x9391C1F2.

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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