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AUSCERT External Security Bulletin Redistribution
ESB-2005.0173 -- IBM Security Advisory
Format string vulnerability in chdev, mkdev and rmdev
21 February 2005
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AusCERT Security Bulletin Summary
---------------------------------
Product: chdev
mkdev
rmdev
Publisher: IBM
Operating System: AIX 5.1, 5.2 and 5.3
Impact: Root Compromise
Access: Existing Account
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IBM SECURITY ADVISORY
First Issued: Mon Feb 7 14:45:13 CST 2005
|Updated: Thu Feb 10 09:11:29 CST 2005
|Added mkdev and rmdev
|Added interim fix information
==========================================================================
VULNERABILITY SUMMARY
|Updated: Thu Feb 10 09:11:29 CST 2005
|Added mkdev and rmdev
|VULNERABILITY: A format string vulnerability in the mkdev, rmdev
| and chdev commands may allow a local user in the
| system group to gain root privileges.
PLATFORMS: AIX 5.1, 5.2 and 5.3.
|Updated: Thu Feb 10 09:11:29 CST 2005
|Added interim fix information
|SOLUTION: Apply the workaround, interim fix or APARs as
| described below.
THREAT: A local user may gain root privileges.
CERT VU Number: N/A
CVE Number: N/A
==========================================================================
DETAILED INFORMATION
I. Description
===============
|Updated: Thu Feb 10 09:11:29 CST 2005
|Added mkdev and rmdev
|Format string vulnerabilities in the mkdev, rmdev and chdev commands were
|discovered. These vulnerability may allow a local user in the system
|group to gain root privileges.
The commands affected by this issue ship as part of the bos.rte.methods
fileset. To determine if this fileset is installed, execute the following
command:
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 may gain root privileges.
III. Solutions
===============
A. Official Fix
IBM provides the following fixes:
APAR number for AIX 5.1.0: IY67741 (available approx. 03/23/05)
APAR number for AIX 5.2.0: IY67455 (available approx. 04/15/05)
APAR number for AIX 5.3.0: IY67654 (available approx. 04/15/05)
NOTE: Affected customers are urged to upgrade to 5.1.0, 5.2.0 or 5.3.0 at
the latest maintenance level.
|Updated Thu Feb 10 09:11:29 CST 2005
|Added interim fix information
|B. Emergency Fix
|
|Efixes are available for AIX 5.1.0, 5.2.0 and 5.3.0. The efixes can be
|downloaded via ftp from:
|
| ftp://aix.software.ibm.com/aix/efixes/security/dev_efix.tar.Z
|
|dev_efix.tar.Z is a compressed tarball containing this advisory, three
|efix packages cleartext PGP signatures for each efix package.
|
|
|Verify you have retrieved the efixes intact:
|----------------------------------------------
|The checksums below were generated using the "sum" and "md5sum" commands
|and are as follows:
|
|Filename sum md5
|======================================================================
|IY67741.050209.epkg.Z 07350 39 314e11508582e6c406416c9028d5cab4
|IY67455.050209.epkg.Z 19517 41 4dd644283c8708728aacf9fb52839d46
|IY67654.050209.epkg.Z 63018 45 fb86a416d5c775cd58a2a105d5314458
|
|
|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 efixes have not been fully regression tested; thus, IBM does not
|warrant the fully correct functioning of the efix. Customers install the
|efix and operate the modified version of AIX at their own risk.
|
|Efix Installation Instructions:
|-------------------------------
|These packages use the new Emergency Fix Management Solution to install
|and manage efixes. More information can be found at:
|
| http://techsupport.services.ibm.com/server/aix.efixmgmt
|
|To preview an epkg efix installation execute the following command:
|
|# emgr -e epkg_name -p # where epkg_name is the name of the
| # efix package being previewed.
|
|To install an epkg efix package, execute the following command:
|
|# emgr -e epkg_name -X # where epkg_name is the name of the
| # efix package being installed.
|
|The "X" flag will expand any filesystems if required.
C. Workaround
Setting the file mode bits to 500 will allow only the root user to execute
the chdev command. This can be done by executing the following command as
root:
# chmod 500 /usr/sbin/chdev
Verify that the file mode bits have been changed to 500:
# ls -la /usr/sbin/chdev
- - -r-x------ 1 root system 22238 2003-05-02 01:19 /usr/sbin/chdev
|Updated: Thu Feb 10 09:11:29 CST 2005
|Added mkdev and rmdev
|These steps should be repeated for the mkdev and rmdev commands.
IV. Obtaining Fixes
===================
AIX Version 5 APARs can be downloaded from:
http://www-1.ibm.com/servers/eserver/support/pseries/aixfixes.html
Security related Emergency Fixes can be downloaded from:
ftp://aix.software.ibm.com/aix/efixes/security
V. Acknowledgments
====================
This vulnerability was reported by iDEFENSE.
VI. 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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