Summary

Vulnerabilities in OpenSSL could allow a remote attacker to cause a denial of service (CVE-2023-5678, CVE-2023-6129, CVE-2023-6237) or obtain sensitive information (CVE-2023-5363). OpenSSL is used by AIX as part of AIX’s secure network communications.

Vulnerability Details

**CVEID:**CVE-2023-5363 DESCRIPTION: OpenSSL could allow a remote attacker to obtain sensitive information, caused by an incorrect cipher key and IV length processing during the initialisation of some symmetric ciphers. By sending a specially crafted request, an attacker could exploit this vulnerability to obtain sensitive information, and use this information to launch further attacks against the affected system.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/269418 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)

**CVEID:**CVE-2023-5678 DESCRIPTION: Openssl is vulnerable to a denial of service, caused by a flaw when using DH_generate_key() function to generate an X9.42 DH key. By sending a specially crafted request, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 3.7
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/270771 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L)

**CVEID:**CVE-2023-6129 DESCRIPTION: OpenSSL is vulnerable to a denial of service, caused by a flaw in the POLY1305 MAC (message authentication code) implementation. By sending a specially crafted request, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/278934 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)

**CVEID:**CVE-2023-6237 DESCRIPTION: OpenSSL is vulnerable to a denial of service, caused by a flaw in the handling of RSA public keys by the EVP_PKEY_public_check() function. By persuading a victim to sue a specially crafted RSA public keys for verification, a remote attacker could exploit this vulnerability to cause long delays, and results in a denial of service condition.
CVSS Base score: 3.1
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/279450 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L)

Affected Products and Versions

The following fileset levels are vulnerable:

Note:

A. 0.9.8, 1.0.1 OpenSSL versions are out-of-support. Support for OpenSSL 1.0.2 version ended in December 2023. Customers are advised to upgrade to OpenSSL 1.1.1 or 3.0 version.

B. Latest level of OpenSSL fileset is available from the web download site:

https://www.ibm.com/resources/mrs/assets?source=aixbp&S_PKG=openssl

C. CVE-2023-5363, CVE-2023-6129, and CVE-2023-6237 only apply to OpenSSL 3.0 version.

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

Example: lslpp -L | grep -i openssl.base

Remediation/Fixes

A. FIXES

IBM strongly recommends addressing the vulnerability now.

The fixes can be downloaded via ftp or http from:

https://aix.software.ibm.com/aix/efixes/security/openssl_fix40.tar

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.

Note that the tar file contains Interim fixes that are based on OpenSSL version, and AIX OpenSSL fixes are cumulative. If an OpenSSL fileset with VMRF higher than the affected level listed above is available from the web download site, then that fileset is the recommended remediation. The OpenSSL 1.0.2 version shared objects provided in the library of OpenSSL 1.1.1 version is remediated.

Applying the fix addresses all OpenSSL vulnerabilities reported up to and including community OpenSSL versions 1.0.2zj, 1.1.1x, and 3.0.13.

You must be on the ‘prereq for installation’ level before applying the interim fix. This may require installing a new level(prereq version) first.

To extract the fixes from the tar file:

tar xvf openssl_fix40.tar

cd openssl_fix40

Verify you have retrieved the fixes intact:

The checksums below were generated using the “openssl dgst -sha256 [file]” 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 AIX Support at https://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:

https://aix.software.ibm.com/aix/efixes/security/openssl_advisory40.asc.sig

B. FIX AND INTERIM FIX INSTALLATION

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:

https://www.ibm.com/support/pages/managing-interim-fixes-aix

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