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===========================================================================
AUSCERT External Security Bulletin Redistribution
ESB-2012.1015
AIX ftp vulnerability
23 October 2012
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: ftp
Publisher: IBM
Operating System: AIX
Impact/Access: Access Privileged Data -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2012-4845
Original Bulletin:
http://aix.software.ibm.com/aix/efixes/security/ftp_advisory1.asc
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IBM SECURITY ADVISORY
First Issued: Thu Oct 18 09:50:27 CDT 2012
The most recent version of this document is available here:
http://aix.software.ibm.com/aix/efixes/security/ftp_advisory1.asc
===============================================================================
VULNERABILITY SUMMARY
VULNERABILITY: AIX ftp vulnerability
PLATFORMS: AIX 6.1 and 7.1 releases
SOLUTION: Apply the fix as described below.
THREAT: See below
CVE Numbers: CVE-2012-4845
Reboot required? YES
Workarounds? YES
Protected by FPM? NO
Protected by SED? NO
===============================================================================
DETAILED INFORMATION
I. DESCRIPTION
The ftp client is allowed to read files that the user running ftp is
not authorized to read. This can result in a non-root user having access
to root only files. The problem is actually a setuid issue.
The issue is that ftp is currently doing both switching uids and flipping
privileges. Before RBAC was implemented, setuid was used to flip uids
and since there was no real privilege concept, it served as both purposes.
Now after RBAC has been introduced, privileges are key attributes and uid is
kept only for backward compatibility and switching uids is not really
needed, but ftp is still doing it.
The problem only shows up in commands such as ftp, where secflags is not set
to FSF_EPS in the privcmds database.
II. CVSS
CVSS Base Score: 6.8
CVSS Temporal Score: See http://xforce.iss.net/xforce/xfdb/79279 for the
current score
CVSS Environmental Score*: Undefined
CVSS String: (AV:N/AC:L/Au:S/C:C/I:N/A:N)
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.mp64 bos.rte.tty
The following fileset levels are vulnerable:
AIX Fileset Lower Level Upper Level
------------------------------------------------------------------
bos.mp64 6.1.6.0 6.1.6.20
bos.rte.tty 6.1.6.0 6.1.6.19
bos.mp64 6.1.7.0 6.1.7.16
bos.rte.tty 6.1.7.0 6.1.7.16
bos.mp64 7.1.0.0 7.1.0.20
bos.rte.tty 7.1.0.0 7.1.0.18
bos.mp64 7.1.1.0 7.1.1.16
bos.rte.tty 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 IV28715 12/12/12 sp10
6.1.7 IV23331 12/12/12 sp6
7.1.0 IV28785 12/12/12 sp8
7.1.1 IV28787 12/12/12 sp6
Subscribe to the APARs here:
http://www.ibm.com/support/docview.wss?uid=isg1IV28715
http://www.ibm.com/support/docview.wss?uid=isg1IV23331
http://www.ibm.com/support/docview.wss?uid=isg1IV28785
http://www.ibm.com/support/docview.wss?uid=isg1IV28787
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/ftp_fix1.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 IV28715m09.121012.epkg.Z
6.1.7.5 IV23331m05.121003.epkg.Z
7.1.0.7 IV28785m07.121002.epkg.Z
7.1.1.5 IV28787m05.121002.epkg.Z
VIOS Level Interim Fix (*.Z)
-------------------------------------------------------------------
VIOS 2.2.1.4-FP-25 SP-02 IV23331m04.121003.epkg.Z
To extract the fixes from the tar file:
tar xvf ftp_fix1.tar
cd ftp_fix1
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
------------------------------------------------------------------
4ba2810c2f7b909d9c9d6aa9aa2c8598ae5cd3c9 IV28715m09.121012.epkg.Z
6a5378ebfd9fc9172705798c6763b73b86385188 IV23331m05.121003.epkg.Z
e8ef9337f5460b7b2b2c6334727721a07d0400e1 IV28785m07.121002.epkg.Z
4296229d6731a9f1862502aa6a5a86f785bebcf0 IV28787m05.121002.epkg.Z
bcf1d9b2a661255b90bbe8aa85e7ddf56a6ce5ca IV23331m04.121003.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
Disable the ftp service by modifying the /etc/inetd.conf file to
comment out the "ftp service" line from, for example:
ftp stream tcp6 nowait root /usr/sbin/ftpd ftpd
to
#ftp stream tcp6 nowait root /usr/sbin/ftpd ftpd
And then restart the internet service daemon (inetd):
refresh -s inetd
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/79279
CVE-2012-4845: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-4845
*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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