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UNIRAS Brief - 288/06 - IBM SECURITY ADVISORY: mklvcopy allows users in the system group to execute arbitrary code



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   UNIRAS (UK Govt CERT) Briefing Notice - 288/06 dated 19.04.06  Time: 14:10  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
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  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
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Title
=====

IBM SECURITY ADVISORY: mklvcopy allows users in the system group to execute 
arbitrary code

Detail
====== 

A vulnerability was discovered in the mklvcopy command that allows a local
user in the system group to execute arbitrary code. The mklvcopy command is
used to increase the number of copies in each logical partition of a
logical volume.


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===========================================================================
             

                          ESB-2006.0270 -- [AIX]
    mklvcopy allows users in the system group to execute arbitrary code
                               18 April 2006

===========================================================================

       

Product:           mklvcopy
Publisher:         IBM
Operating System:  AIX 5.1, 5.2 and 5.3
Impact:            Root Compromise
Access:            Existing Account
CVE Names:         CVE-2006-1246

Comment: AIX 5.1, 5.2 and 5.3 are affected by this vulnerability. Only
         version 5.3 is mentioned in this advisory, however the APARS are
         available for all three versions.

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IBM SECURITY ADVISORY


First Issued: Mon Apr 17 10:20:50 CDT 2006
==========================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:      A user in the system group may execute arbitrary code
                    with root privileges.

PLATFORMS:          AIX 5.3.

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

THREAT:             A  user in the system group may execute arbitrary code
                    with root privileges.

CERT VU Number:     n/a 
CVE Number:         CVE-2006-1246
=========================================================================
                           DETAILED INFORMATION


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

A vulnerability was discovered in the mklvcopy command that allows a local
user in the system group to execute arbitrary code. The mklvcopy command is
used to increase the number of copies in each logical partition of a
logical volume.

mklvcopy ships as part of the bos.rte.lvm fileset.


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

A local user in the system group may execute arbitrary code with root
privileges.


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

A. Official Fix

IBM provides the following fixes:

      APAR number for AIX 5.3.0: IY82739 (available)

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

B. Interim Fix

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

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

mklvcopy_ifix.tar.Z is a compressed tarball containing this advisory,
ifix packages and cleartext PGP signatures for each ifix 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
========================================================================
IY82739_02.060313.epkg.Z  59853    14   7b9c54e62d34b80edd03caeb81378b11
IY82739_03.060313.epkg.Z  00809    14   1a43e0029c87bf2dbbdf3762c693d434

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.


The following table shows the prerequisite lower and upper fileset levels
for the fixes above. These levels are inclusive and apply to
bos.rte.lvm.

Technology  Filename                    Lower Level     Upper Level
Level
===================================================================
5300-02     IY82739_02.060313.epkg.Z    5.3.0.10        5.3.0.29 
5300-03     IY82739_03.060313.epkg.Z    5.3.0.30        5.3.0.39


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

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


C. Workaround

Make mklvcopy executable only by the root user
+---------------------------------------------

To make mklvcopy executable only by root, run the following commands:

# chmod 500 /usr/sbin/mklvcopy

Verify the that the file mode bits have been updated:

# ls -la /usr/sbin/mklvcopy
- - - -r-x------   1 root     system        19354 Feb 15 10:25 /usr/sbin/mklvcopy

Note that users in the system group will not be able to use the mklvcopy
command.


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@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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UNIRAS wishes to acknowledge the contributions of IBM for the information 
contained in this Briefing. 
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This Briefing contains the information released by the original author. Some 
of the information may have changed since it was released. If the vulnerability 
affects you, it may be prudent to retrieve the advisory from the site of the
original source to ensure that you receive the most current information concerning 
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<End of UNIRAS Briefing>

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