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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                          ESB-2006.0692 -- [AIX]
         Vulnerabilities in utape may allow for arbitrary command
                  execution and arbitrary file overwrite
                             26 September 2006

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

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              utape
Publisher:            IBM
Operating System:     AIX 5.3 and 5.2
Impact:               Root Compromise
                      Denial of Service
Access:               Existing Account

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IBM SECURITY ADVISORY


First Issued: Mon Sep 25 10:00 CDT 2006
==========================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:      Arbitrary file overwrite and incomplete path
                    vulnerabilities in utape command.

PLATFORMS:          AIX 5.2 and 5.3.

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

THREAT:             A local user may cause a denial of service or execute
                    arbitrary commands with root privileges.

CERT VU Number:     n/a
CVE Number:         n/a
==========================================================================
                           DETAILED INFORMATION


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

Two vulnerabilities exist in the utape command. These vulnerabilities can
only be exploited by a user if that user is both in the system group and
has the "Diagnostics" role. First, a vulnerability exists that will allow a
local user to execute arbitrary commands with root privileges. Second, a
vulnerability exists that will allow a local user to overwrite an arbitrary
system file resulting in a denial of service.

utape ships as part of the devices.scsi.tape.diag fileset. To determine if
this fileset is installed, execute the following command:

# lslpp -L devices.scsi.tape.diag

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

The following table shows the vulnerable versions of
devices.scsi.tape.diag:

AIX Release          Lower         Upper
                     Level         Level
===========================================
AIX 5.2              5.2.0.0       5.2.0.75
AIX 5.3              5.3.0.0       5.3.0.30


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

A local user may execute arbitrary commands or overwrite an arbitrary file
resulting in a denial of service.


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

A. APARs

IBM provides the following fixes:

      APAR number for AIX 5.2.0:  IY88641 (available approx. 10/18/06)
      APAR number for AIX 5.3.0:  IY88642 (available approx. 11/01/06)

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/utape_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
=========================================================================
IY88641_07.060824.epkg.Z   49985    25   3109a163f3b09041b431866988c3f332
IY88641_08.060824.epkg.Z   47659    25   4b077a04542e9e77c6f5424f098e52e0
IY88641_09.060824.epkg.Z   44860    25   ced7d54998885cbd225289d0e07b4683
IY88642_03.060824.epkg.Z   48193    25   eeafca7b458be572f271e2d9ca43cb3a
IY88642_04.060824.epkg.Z   21572    25   ae72e10aacbd0263e4ebf3d4e063ae79
IY88642_05.060824.epkg.Z   27641    25   68d846f354bce4ba704954f7e54cd1a8

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 devices.scsi.tape.diag.

Interim                    Fileset Level     Fileset Level
Fix                        (lower limit)     (upper limit)
===================================================================
IY88641_07.060824.epkg.Z   5.2.0.75          5.2.0.75
IY88641_08.060824.epkg.Z   5.2.0.75          5.2.0.75
IY88641_09.060824.epkg.Z   5.2.0.75          5.2.0.75
IY88642_03.060824.epkg.Z   5.3.0.30          5.3.0.30
IY88642_04.060824.epkg.Z   5.3.0.30          5.3.0.30
IY88642_05.060824.epkg.Z   5.3.0.30          5.3.0.30

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

Remove the setuid root bit. Note that this will prevent utape from
functioning normally for non-root users. This can be done by executing the
following command:

# chmod 550 /usr/lpp/diagnostics/bin/utape

Verify the changes:

# ls -la /usr/lpp/diagnostics/bin/utape
- - -r-xr-x---   1 root     system        36580 Oct  1 2004 
/usr/lpp/diagnostics/bin/utape


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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