Date: Mon, 26 Oct 1998 09:12:02 -0500
From: [email protected]
To: [email protected]Subject: IBM-ERS Security Vulnerability Alert: IBM AIX: automountd daemon
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EMERGENCY RESPONSE SERVICE
SECURITY VULNERABILITY ALERT
26 October 1998 14:00 GMT Number: ERS-SVA-E01-1998:004.1
VULNERABILITY SUMMARY
VULNERABILITY: The automountd daemon allows local and remote users to become
root.
PLATFORMS: IBM AIX(r) 4.3.x
SOLUTION: Apply the fixes listed below.
THREAT: Remote users can execute arbitrary commands as root.
DETAILED INFORMATION
I. Description
The automountd daemon processes requests from the local AutoFS filesystem
kernel extension. It uses local files or name service maps to locate file
systems to be mounted. Because the daemon does not verify that requests
are actually from the kernel extension, local non-root users and remote
users can request automountd services.
II. Impact
If the automountd daemon is active, local and remote users can cause
arbitrary commands to run as root. Exploits for this problem have been
made publicly available.
To determine if the daemon is active on your system, run the following
command:
$ lssrc -s automountd
To disable the daemon until the fix can be applied (run as root):
# stopsrc -s automountd
III. Solutions
A. Official fix
IBM is working on the following fixes which will be available soon.
AIX 4.1.x: not vulnerable
AIX 4.2.x: not vulnerable
AIX 4.3.x: IX83752
B. How to alleviate the problem
A temporary fix is available via anonymous ftp from:
ftp://aix.software.ibm.com/aix/efixes/security/automountd.tar.Z
Filename sum md5
autofs.ext 26103 117 4afedf8fbe411e8be2588fa8843211ae
automountd 16386 83 eb4c2e1c4cfe609b2ecba0c6a704640c
NOTE - This temporary fix has not been fully regression tested.
Use the following steps (as root) to install the temporary fix:
1. Determine the version of the NFS fileset on your machine.
# lslpp -l bos.net.nfs.client
The version of the fileset for your machine should be at 4.3.1.4
or higher. If not, install requisite APAR IX81896. This will
help ensure that the temporary fix will run properly.
2. Uncompress and extract the fix.
# uncompress < automountd.tar.Z | tar xf -
# cd automountd
3. Replace the vulnerable executables with the temporary fix.
# (cd /usr/lib/drivers && mv autofs.ext autofs.ext.before_security_fix)
# (cd /usr/sbin && mv automountd automountd.before_security_fix)
# chmod 0 /usr/lib/drivers/autofs.ext.before_security_fix
# chmod 0 /usr/sbin/automountd.before_security_fix
# cp ./autofs.ext /usr/lib/drivers/autofs.ext
# cp ./automountd /usr/sbin/automountd
# chown root.system /usr/sbin/automountd /usr/lib/drivers/autofs.ext
# chmod 555 /usr/sbin/automountd /usr/lib/drivers/autofs.ext
4. Reboot.
IV. Obtaining Fixes
IBM AIX APARs may be ordered using Electronic Fix Distribution (via the
FixDist program), or from the IBM Support Center. For more information
on FixDist, and to obtain fixes via the Internet, please reference
http://aix.software.ibm.com/support/rs6000
or send email to "[email protected]" with the word "FixDist" in the
"Subject:" line.
To facilitate ease of ordering all security related APARs for each AIX
release, security fixes are periodically bundled into a cumulative APAR.
For more information on these cumulative APARs including last update and
list of individual fixes, send email to "[email protected]" with
the word "subscribe Security_APARs" in the "Subject:" line.
V. Acknowledgements
Thanks to Repent Security Incorporated for bringing this problem to
our attention. A copy of their autofsd advisory can be found at
http://www.repsec.com/.
VI. Contact Information
Comments regarding the content of this announcement can be directed to
your local IBM support center or to:
[email protected]
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Copyright 1998 International Business Machines Corporation.
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