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AUSCERT External Security Bulletin Redistribution
ESB-2005.0990 -- [AIX]
A user in the system group with RunDiagnostics role can
execute arbitrary code
16 December 2005
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: diagela
Publisher: IBM
Operating System: AIX
Impact: Execute Arbitrary Code/Commands
Access: Existing Account
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IBM SECURITY ADVISORY
First Issued: Thu Dec 15 09:00:44 CST 2005
==========================================================================
VULNERABILITY SUMMARY
VULNERABILITY: A local user in the system group with the
RunDiagnostics role can execute arbitrary code.
PLATFORMS: AIX 5.1, 5.2 and 5.3.
SOLUTION: Apply the APAR, interim fix or workaround as
described below.
THREAT: A local user may execute arbitrary code.
CERT VU Number: N/A
CVE Number: N/A
=========================================================================
DETAILED INFORMATION
I. Description
===============
A vulnerability was discovered in the diagela script that allows a local
user that is in the system group and that has the RunDiagnostics role to
execute arbitrary code. Exploits for this vulnerability may be publicly
available.
The command affected by this issue ships as part of the bos.diag.rte
fileset. To determine if this fileset is installed, execute the following
command:
# lslpp -L bos.diag.rte
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 with the RunDiagnostics role can execute
arbitrary code.
III. Solutions
===============
A. Official Fix
IBM provides the following fixes:
APAR number for AIX 5.1.0: IY78926 (available approx. 01/18/06)
APAR number for AIX 5.2.0: IY78800 (available approx. 01/30/06)
APAR number for AIX 5.3.0: IY78801 (available approx. 01/30/06)
NOTE: Affected customers are urged to upgrade to 5.1.0, 5.2.0 or 5.3.0 at
the latest maintenance level.
B. Interim Fix
Interim fixes are available for AIX 5.1.0, 5.2.0 and 5.3.0. The ifixes can
be downloaded via ftp from:
ftp://aix.software.ibm.com/aix/efixes/security/diagela_ifix.tar.Z
diagela_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 maintenance 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
========================================================================
IY78926_09.051114.epkg.Z 24109 15 5aa6f69cb12fa758b634102e5afe4f6e
IY78800_05.051111.epkg.Z 38413 16 aaa731994f6f4b09130776999132fab0
IY78800_06.051111.epkg.Z 09920 16 45e69cde7159844f03cba1765cda888e
IY78800_07.051111.epkg.Z 02376 16 1bfd12cea05f8b3ec0c2ae9a60900c78
IY78801_01.051111.epkg.Z 41809 16 223434e1859ff2c77dbe0fc38e8093dd
IY78801_02.051111.epkg.Z 40981 16 a87ce306026e96cb2c998108fa2cb5a7
IY78801_03.051111.epkg.Z 48032 16 785f52be01224e9fbe80129e628e72a1
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.
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://techsupport.services.ibm.com/server/aix.efixmgmt
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
Changing diagela_exec file mode bits
- - ------------------------------------
Setting the file mode bits of diagela_exec to 500 will allow only the root
user to execute the diagela script to carry out diagnostics This can be
done by executing the following command as root:
# chmod 500 /usr/lpp/diagnostics/bin/diagela_exec
Verify that the file mode bits have been updated:
# cd /usr/lpp/diagnostics/bin
# ls -la diagela_exec
- - -r-x------ 1 root system 3578 Aug 28 2004 diagela_exec
The diagela script uses to the diagela_exec command. Changing the file
permissions of diagela_exec to 500 implies that only the root users will be
able to use diagela properly.
Assign the RunDiagnostics role to trusted users
- - -----------------------------------------------
A user must be in the system group and have the RunDiagnostics role to
exploit this vulnerability. This vulnerability can be mitigated by ensuring
that only trusted users have this role. This workaround will not totally
protect against this vulnerability being exploited unless all users are
removed from the RunDiagnostics role.
IV. Obtaining Fixes
===================
AIX Version 5 APARs can be downloaded from:
http://www-1.ibm.com/servers/eserver/support/pseries/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:
https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs
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 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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