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Security Bulletin: Vulnerability in lscore affects AIX (CVE-2021-38991)

Security Bulletin


Summary

There is a vulnerability in the lscore command that affects AIX.

Vulnerability Details

CVEID:   CVE-2021-38991
DESCRIPTION:   IBM AIX could allow a non-privileged local user to exploit a vulnerability in the lscore command which could lead to code execution.
CVSS Base score: 8.4
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/212953 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.rte.security 7.1.5.0 7.1.5.37
bos.rte.security 7.2.4.0 7.2.4.3
bos.rte.security 7.2.5.0 7.2.5.1
bos.rte.security 7.2.5.100 7.2.5.101
bos.rte.security 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.rte.security

Remediation/Fixes

A. APARS
         
IBM has assigned the following APARs to this problem:
AIX Level APAR SP
7.1.5 IJ36805 SP10
7.2.4 IJ36806 SP06
7.2.5 IJ36810 SP04
7.3.0 IJ36816 SP02

VIOS Level APAR SP
3.1.1 IJ36806 3.1.1.60
3.1.2 IJ36815 3.1.2.40
3.1.3 IJ36810 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.
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 IJ36805s9a.211217.epkg.Z
7.1.5.8 IJ36805s9a.211217.epkg.Z
7.1.5.9 IJ36805s9a.211217.epkg.Z
7.2.4.2 IJ36806s2a.211217.epkg.Z
7.2.4.3 IJ36806s4a.211217.epkg.Z
7.2.4.4 IJ36806s4a.211217.epkg.Z
7.2.5.1 IJ36815s2a.211217.epkg.Z
7.2.5.2 IJ36815s2a.211217.epkg.Z
7.2.5.3 IJ36810s3a.211217.epkg.Z
7.3.0.1 IJ36816s1a.211217.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
3.1.1.21 IJ36806s2a.211217.epkg.Z
3.1.1.25 IJ36806s2a.211217.epkg.Z
3.1.1.30 IJ36806s4a.211217.epkg.Z
3.1.1.40 IJ36806s4a.211217.epkg.Z
3.1.2.10 IJ36815s2a.211217.epkg.Z
3.1.2.21 IJ36815s2a.211217.epkg.Z
3.1.3.10 IJ36810s3a.211217.epkg.Z
3.1.3.14 IJ36810s3a.211217.epkg.Z
To extract the fixes from the tar file:
tar xvf lscore_fix.tar
cd lscore_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
866141e4fcc92ecbfff15e3c216347f8788a84bba558647b53256acdf338c4dd IJ36805s9a.211217.epkg.Z
8be118a07a65509c99d09c7cd0b8e55f9eb192a0ceff7f73beb973031f405515 IJ36806s2a.211217.epkg.Z
870448503c15caabb138e93d4d7e32348af51f8ef4db0cf35047876a5da0f68a IJ36806s4a.211217.epkg.Z
c8cf7f12d62220e44d22360cfc408bb6e3d090c3401429cddb4a4bf1e6c5160e IJ36810s3a.211217.epkg.Z
428938e255b869354fbd4e43f007b4e7224cdeb43d9ec1cc7cfecbfb18a244cc IJ36815s2a.211217.epkg.Z
eb681a0a23855b1805b6d5d111f5bb50faf318221b29e9af016ae3d410d9efa8 IJ36816s1a.211217.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
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

Acknowledgement

Change History

10 Jan 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.

Document Location

Worldwide

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Document Information

Modified date:
10 January 2022

UID

ibm16538952