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AUSCERT External Security Bulletin Redistribution
ESB-2012.0947
AIX fuser vulnerability
3 October 2012
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: AIX
Publisher: IBM
Operating System: AIX
Impact/Access: Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2012-4833
Original Bulletin:
http://aix.software.ibm.com/aix/efixes/security/fuser_advisory.asc
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IBM SECURITY ADVISORY
First Issued: Fri Sept 28 13:02:02 CDT 2012
The most recent version of this document is available here:
http://aix.software.ibm.com/aix/efixes/security/fuser_advisory.asc
===============================================================================
VULNERABILITY SUMMARY
VULNERABILITY: AIX fuser vulnerability
PLATFORMS: 6.1 and 7.1 releases
SOLUTION: Apply the fix as described below.
THREAT: See below
CVE Numbers: CVE-2012-4833
Reboot required? NO
Workarounds? NO
Protected by FPM? NO
Protected by SED? NO
===============================================================================
DETAILED INFORMATION
I. DESCRIPTION
IBM AIX is vulnerable to a denial of service, caused by improper
restrictions on the fuser command. A local attacker could exploit this
vulnerability via the -k argument to kill a process of another user.
II. CVSS
CVSS Base Score: 2.1
CVSS Temporal Score: See http://xforce.iss.net/xforce/xfdb/78907 for the
current score
CVSS Environmental Score*: Undefined
CVSS String: (AV:L/AC:L/Au:N/C:N/I:N/A:P)
III. 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.rte.filesystem
The following fileset levels are vulnerable:
AIX Fileset Lower Level Upper Level
--------------------------------------------------------
bos.rte.filesystem 6.1.6.0 6.1.6.19
bos.rte.filesystem 6.1.7.0 6.1.7.16
bos.rte.filesystem 7.1.0.0 7.1.0.18
bos.rte.filesystem 7.1.1.0 7.1.1.16
IV. SOLUTIONS
A. APARS
IBM has assigned the following APARs to this problem:
AIX Level APAR number Availability
---------------------------------------------------
6.1.6 IV28151 12/12/12 sp10
6.1.7 IV28749 12/12/12 sp6
7.1.0 IV28754 12/12/12 sp8
7.1.1 IV28756 12/12/12 sp6
Subscribe to the APARs here:
http://www.ibm.com/support/docview.wss?uid=isg128151
http://www.ibm.com/support/docview.wss?uid=isg128749
http://www.ibm.com/support/docview.wss?uid=isg128754
http://www.ibm.com/support/docview.wss?uid=isg128756
By subscribing, you will receive periodic email alerting you
to the status of the APAR, and a link to download the fix once
it becomes available.
B. FIXES
Fixes are available. The fixes can be downloaded via ftp
from:
ftp://aix.software.ibm.com/aix/efixes/security/fuser_fix.tar
The link above is to a tar file containing this signed
advisory, fix packages, and PGP signatures for each package.
The fixes below include prerequisite checking. This will
enforce the correct mapping between the fixes and AIX
Technology Levels.
AIX Level Interim Fix (*.Z)
-------------------------------------------------------------------
6.1.6.9 IV28151s09.120926.epkg.Z
6.1.7.5 IV28749s05.120926.epkg.Z
7.1.0.7 IV28754s07.120926.epkg.Z
7.1.1.5 IV28756s05.120926.epkg.Z
VIOS Level Interim Fix (*.Z)
-------------------------------------------------------------------
VIOS 2.2.1.4-FP-25 SP-02 IV28749s04.120926.epkg.Z
To extract the fixes from the tar file:
tar xvf fuser_fix.tar
cd fuser_fix
Verify you have retrieved the fixes intact:
The checksums below were generated using the
"csum -h SHA1" (sha1sum) command is the followng:
csum -h SHA1 (sha1sum) filename
------------------------------------------------------------------
c607d32b2e12aa840060001f35526501b976490f IV28151s09.120926.epkg.Z
a0b99ea910bece90a907c2a111d146fa16d64404 IV28749s05.120926.epkg.Z
c8fc384fa720282efe92acb584300ee878c7c926 IV28754s07.120926.epkg.Z
feae51894146d83d589313bf829caf11df30882f IV28756s05.120926.epkg.Z
1e0a8950b6d69c697764080c741af01e7a300b0a IV28749s04.120926.epkg.Z
To verify the sum, use the text of this advisory as input to 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 at
security-alert@austin.ibm.com and describe the discrepancy.
C. FIX AND INTERIM 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.
To preview a fix installation:
installp -a -d fix_name -p all # where fix_name is the name of the
# fix package being previewed.
To install a fix package:
installp -a -d fix_name -X all # where fix_name is the name of the
# fix package being installed.
Interim fixes have had limited functional and regression
testing but not the full regression testing that takes place
for Service Packs; however, IBM does fully support them.
Interim fix management documentation can be found at:
http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html
To preview an interim fix installation:
emgr -e ipkg_name -p # where ipkg_name is the name of the
# interim fix package being previewed.
To install an interim fix package:
emgr -e ipkg_name -X # where ipkg_name is the name of the
# interim fix package being installed.
V. WORKAROUNDS
There are no workarounds.
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
IBM discovered and fixed this vulnerability as part of its
commitment to secure the AIX operating system.
VIII. REFERENCES:
Complete CVSS Guide: http://www.first.org/cvss/cvss-guide.html
On-line Calculator V2: http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2
X-Force Vulnerability Database: http://xforce.iss.net/xforce/xfdb/78907
CVE-2012-4833: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-4833
*The CVSS Environment Score is customer environment specific and will
ultimately impact the Overall CVSS Score. Customers can evaluate the
impact of this vulnerability in their environments by accessing the links
in the Reference section of this Flash.
Note: According to the Forum of Incident Response and Security Teams
(FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry
open standard designed to convey vulnerability severity and help to
determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES
"AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE
RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY
VULNERABILITY.
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