Security Bulletin: AIX is vulnerable to arbitrary command execution due to invscout (CVE-2023-28528)

Summary

A vulnerability in the AIX invscout command could allow a non-privileged local user to execute arbitrary commands (CVE-2023-28528).

Vulnerability Details

CVEID:CVE-2023-28528
**DESCRIPTION:**IBM AIX could allow a non-privileged local user to exploit a vulnerability in the invscout command to execute arbitrary commands.
CVSS Base score: 8.4
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/251207 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

The following fileset levels are vulnerable:

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 invscout.rte

Remediation/Fixes

A. FIXES

IBM strongly recommends addressing the vulnerability now.

AIX and VIOS fixes are available.

The AIX and VIOS fixes can be downloaded via https from:

<https://aix.software.ibm.com/aix/efixes/security/invscout_fix4.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.

For AIX 7.1, 7.2, and VIOS 3.1, you must be on the ‘bos.rte.libc prereq’ level before installing the new invscout.rte package.

To extract the fixes from the tar file:

tar xvf invscout_fix4.tar

cd invscout_fix4

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:

<https://aix.software.ibm.com/aix/efixes/security/invscout_advisory4.asc.sig&gt;

B. 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 the fix installation:

installp -apYd . invscout

To install the fix package:

installp -aXYd . invscout

Workarounds and Mitigations

None