Summary

There is a vulnerability in the AIX trace facility.

Vulnerability Details

CVEID:CVE-2021-29706
**DESCRIPTION:**IBM AIX could allow a non-privileged local user to exploit a vulnerability in the trace facility to expose sensitive information or cause a denial of service.
CVSS Base score: 6.8
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/200663 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H)

Affected Products and Versions

The vulnerabilities in the following filesets are being addressed:

To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in AIX user’s guide.

Example: lslpp -L | grep -i bos.mp64

Remediation/Fixes

A. APARS

IBM has assigned the following APARs to this problem:

Subscribe to the APARs here:

<https://www.ibm.com/support/pages/apar/IJ32940&gt;

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

AIX fixes are available.

An LPAR system reboot is required to complete the iFix installation.

The AIX and VIOS fixes can be downloaded via ftp or http from:

ftp://aix.software.ibm.com/aix/efixes/security/trace_fix.tar

<http://aix.software.ibm.com/aix/efixes/security/trace_fix.tar&gt;

<https://aix.software.ibm.com/aix/efixes/security/trace_fix.tar&gt;

The link above is to a tar file containing this signed advisory, fix packages, and OpenSSL signatures for each package. The fixes below include prerequisite checking. This will enforce the correct mapping between the fixes and AIX Technology Levels.

Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.1.5.7 is AIX 7100-05-07.

NOTE: Multiple iFixes are provided for AIX 7100-05-06, 7100-05-07, and 7100-05-08.
IJ32940m6a is for AIX 7100-05-06 with bos.mp64 fileset level 7.1.5.38.
IJ32940m6b is for AIX 7100-05-06 with bos.mp64 fileset level 7.1.5.37.
IJ32940m7a is for AIX 7100-05-07 with bos.mp64 fileset level 7.1.5.40.
IJ32940m7b is for AIX 7100-05-07 with bos.mp64 fileset level 7.1.5.39.
IJ32940s8a is for AIX 7100-05-08 with bos.mp64 fileset level 7.1.5.42.
IJ32940s8b is for AIX 7100-05-08 with bos.mp64 fileset level 7.1.5.41.

Please reference the Affected Products and Version section above for help with checking installed fileset levels.

The fixes are cumulative and address previously issued AIX kernel security bulletins with respect to SP and TL, which includes:

<https://aix.software.ibm.com/aix/efixes/security/power9_advisory.asc&gt;

<https://www.ibm.com/support/pages/node/6370729&gt;

<https://aix.software.ibm.com/aix/efixes/security/gencore_advisory.asc&gt;

<https://www.ibm.com/support/pages/node/6406022&gt;

To extract the fixes from the tar file:

tar xvf trace_fix.tar

cd trace_fix

Verify you have retrieved the fixes intact:

The checksums below were generated using the “openssl dgst -sha256 [filename]” command as the following:

These sums should match exactly. The OpenSSL 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 Support at <http://ibm.com/support/&gt; and describe the discrepancy.

openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]

openssl dgst -sha256 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file]

Published advisory OpenSSL signature file location:

<http://aix.software.ibm.com/aix/efixes/security/trace_advisory.asc.sig&gt;

<https://aix.software.ibm.com/aix/efixes/security/trace_advisory.asc.sig&gt;

ftp://aix.software.ibm.com/aix/efixes/security/trace_advisory.asc.sig

C. FIX AND INTERIM FIX INSTALLATION

An LPAR system reboot is required to complete the iFix installation.

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&gt;

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.

Workarounds and Mitigations

None