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Security Bulletin: Vulnerability in ksu affects AIX (CVE-2020-4829)

Security Bulletin


Summary

There is a vulnerability in the ksu user command that affects AIX.

Vulnerability Details

CVEID:   CVE-2020-4829
DESCRIPTION:   IBM AIX could allow a local user to exploit a vulnerability in the ksu user command to gain root privileges.
CVSS Base score: 8.4
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/189960 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
VIOS 3.1

The following fileset levels are vulnerable:

Fileset  Lower Level  Upper Level 
krb5.client.rte  1.16.1.0  1.16.1.2

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 krb5.client.rte

Remediation/Fixes

FIXES
AIX and VIOS fixes are available and can be downloaded from:
To extract the fixes from the tar file:
zcat NAS_1.16.1.3_aix_image.tar.Z | tar xvf -
IMPORTANT: If possible, it is recommended that a mksysb backup of the system be created.  Verify it is both bootable and readable before proceeding.
Note that all the previously reported security vulnerability fixes are also included in above mentioned fileset level. Please refer to the readme file (provided along with the fileset) for the complete list of vulnerabilities fixed.
To preview the fix installation:
installp -apYd NAS_1.16.1.3_aix_image krb5
To install the fix package:
installp -aXYd NAS_1.16.1.3_aix_image krb5
openssl dgst -sha1 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]
openssl dgst -sha1 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file]
Published advisory OpenSSL signature file location:

Workarounds and Mitigations

None

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References

Complete CVSS v3 Guide
On-line Calculator v3

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Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

AIX Security Bulletin (ASCII format)

Change History

08 Dec 2020: 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

Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.

Document Location

Worldwide

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Document Information

Modified date:
15 December 2020

UID

ibm16380430

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