Summary

Vulnerabilities in OpenSSL could allow a remote attacker to execute arbitrary code (CVE-2024-4741) or cause a denial of service (CVE-2024-5535, CVE-2024-4603). OpenSSL is used by AIX as part of AIX’s secure network communications.

Vulnerability Details

CVEID:CVE-2024-4741
**DESCRIPTION:**OpenSSL could allow a remote attacker to execute arbitrary code on the system, caused by a use-after-free flaw in the SSL_free_buffers API function . By sending a specially crafted request, an attacker could exploit this vulnerability to execute arbitrary code or cause a denial of service condition.
CVSS Base score: 8.1
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/292512 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)

CVEID:CVE-2024-5535
**DESCRIPTION:**OpenSSL is vulnerable to a denial of service, caused by a buffer over-read flaw in the SSL_select_next_proto API function when calling with an empty supported client protocols buffer. By sending a specially crafted request, a remote attacker could exploit this vulnerability to cause a crash or memory contents to be sent to the peer.
CVSS Base score: 3.7
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/296011 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-2024-4603
**DESCRIPTION:**OpenSSL is vulnerable to a denial of service, caused by improper input validation by the EVP_PKEY_param_check() or EVP_PKEY_public_check() function. By parsing a specially crafted DSA public key or DSA parameters, a remote attacker could exploit this vulnerability to cause long delays, and results in a denial of service condition.
CVSS Base score: 3.7
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/290839 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)

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. CVE-2024-4603 only applies 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 https from:

<https://aix.software.ibm.com/aix/efixes/security/openssl_fix42.tar&gt;

The links above are 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.

You must be on the ‘prereq for installation’ level before applying the interim fix. This may require installing a new level(prereq version) first. The latest level of OpenSSL fileset is available from the web download site:
https://www.ibm.com/resources/mrs/assets?source=aixbp&S_PKG=openssl

To extract the fixes from the tar file:

tar xvf openssl_fix42.tar

cd openssl_fix42

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/&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/openssl_advisory42.asc.sig&gt;

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&gt;

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