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Security Bulletin: Vulnerability in the AIX kernel (CVE-2021-38989)

Security Bulletin


Summary

There is a vulnerability in the AIX pmsvcs kernel extension.

Vulnerability Details

CVEID:   CVE-2021-38989
DESCRIPTION:   IBM AIX could allow a non-privileged local user to exploit a vulnerability in the AIX kernel to cause a denial of service.
CVSS Base score: 6.2
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/212951 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Affected Products and Versions

Affected Product(s) Version(s)
AIX 7.1
AIX 7.2
AIX 7.3
VIOS 3.1

The vulnerabilities in the following filesets are being addressed:

Fileset Lower Level Upper Level
bos.pmapi.pmsvcs 7.1.5.0 7.1.5.36
bos.pmapi.pmsvcs 7.2.4.0 7.2.4.4
bos.pmapi.pmsvcs 7.2.5.0 7.2.5.1
bos.pmapi.pmsvcs 7.2.5.100 7.2.5.100
bos.pmapi.pmsvcs 7.3.0.0 7.3.0.0

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.pmapi.pmsvcs

Remediation/Fixes

A. APARS
       
IBM has assigned the following APARs to this problem:
AIX Level APAR SP
7.1.5 IJ37507 SP10
7.2.4 IJ37503 SP06
7.2.5 IJ37488 SP04
7.3.0 IJ37411 SP02
 
VIOS Level APAR SP
3.1.1 IJ37503 3.1.1.60
3.1.2 IJ37778 3.1.2.40
3.1.3 IJ37488 3.1.3.20

Subscribe to the APARs here:

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 and VIOS fixes are available.
An LPAR system reboot is required to complete the iFix installation, or Live Update may be used on AIX 7.2 and 7.3 to avoid a reboot.
The AIX and VIOS fixes can be downloaded via ftp or http from:
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.
AIX Level Interim Fix
7.1.5.7 IJ37507s7a.220215.epkg.Z
7.1.5.8 IJ37507s9a.220215.epkg.Z
7.1.5.9 IJ37507s9a.220215.epkg.Z
7.2.4.3 IJ37503s3a.220215.epkg.Z
7.2.4.4 IJ37503s4a.220215.epkg.Z
7.2.4.5 IJ37503s5a.220215.epkg.Z
7.2.5.1 IJ37778s1a.220215.epkg.Z
7.2.5.2 IJ37778s2a.220215.epkg.Z
7.2.5.3 IJ37488s3a.220215.epkg.Z
7.3.0.1 IJ37411s1a.220215.epkg.Z

Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.2.5.2 is AIX 7200-05-02.
Please reference the Affected Products and Version section above for help with checking installed fileset levels.
VIOS Level Interim Fix
3.1.1.30 IJ37503s3a.220215.epkg.Z
3.1.1.40 IJ37503s4a.220215.epkg.Z
3.1.1.50 IJ37503s5a.220215.epkg.Z
3.1.2.10 IJ37778s1a.220215.epkg.Z
3.1.2.21 IJ37778s2a.220215.epkg.Z
3.1.3.10 IJ37488s3a.220215.epkg.Z
3.1.3.14 IJ37488s3a.220215.epkg.Z

To extract the fixes from the tar file:
tar xvf pmsvcs_fix.tar
cd pmsvcs_fix
Verify you have retrieved the fixes intact:
The checksums below were generated using the "openssl dgst -sha256 [filename]" command as the following:
openssl dgst -sha256 filename
29b84342adb40a9c08ade21c9dded96fc3ec32d9f70a6ece5fa57d4699c486f3 IJ37411s1a.220215.epkg.Z
3313f5c8b50dcd6da5d3608067e05ba1613705bb1c99f67f4e3056e59124613a IJ37488s3a.220215.epkg.Z
9e8df6fdb2a9d40ffc5ce7626f9773efdce5e5226bd56d73692c44a11eb2c0be IJ37503s3a.220215.epkg.Z
d8411b04c81f4c480067a76b232c5261a6d6f0fcdab7011516b2b2f52b911f45 IJ37503s4a.220215.epkg.Z
b29cb115e719fd68003fa9e6a75325bfbbfc75476227484025db687c9ca62e68 IJ37503s5a.220215.epkg.Z
a75e023ab616b3fb3806cf05ffed2924acb3b172b2a696479ec2f0d1428193ef IJ37507s7a.220215.epkg.Z
5b9456fa0b9b46f8546b9149c04419fd6205948e412383c614953d3c37078f5c IJ37507s9a.220215.epkg.Z
34250efd1c456050bfd8588c85642d1b4a0b5634a9ed5091f7f2983db3a92cfc IJ37778s1a.220215.epkg.Z
2257aad1a356934059dbd7e583e125a0da7ce721cf161e2ae880f0f8bfa95b8a IJ37778s2a.220215.epkg.Z

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/ 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:
C. FIX AND INTERIM FIX INSTALLATION
An LPAR system reboot is required to complete the iFix installation, or Live Update may be used on AIX 7.2 to avoid a reboot.
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:
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

Get Notified about Future Security Bulletins

References

Off

Change History

04 Mar 2022: Initial Publication

*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 Security Bulletin.

Disclaimer

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. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.

Document Location

Worldwide

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Document Information

Modified date:
07 March 2022

UID

ibm16561277