Summary

Vulnerability in cURL libcurl could allow a remote attacker to bypass security restrictions (CVE-2024-0853). AIX uses cURL libcurl as part of rsyslog, LV/PV encryption integration with HPCS and in Live Update for interacting with HMC.

Vulnerability Details

CVEID:CVE-2024-0853
**DESCRIPTION:**cURL libcurl could allow a remote authenticated attacker to bypass security restrictions, caused by a flaw with keeping the SSL session ID for connections in its cache even when the verify status (OCSP stapling) test failed. By sending a specially crafted request, an attacker could exploit this vulnerability to bypass OCSP verification.
CVSS Base score: 3.8
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/281082 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N)

Affected Products and Versions

The following fileset levels are vulnerable:

Note: This bulletin does not apply to versions of curl installed from the AIX Toolbox.

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 oss.lib.libcurl

Remediation/Fixes

A. FIXES

IBM strongly recommends addressing the vulnerability now.

AIX fixes are available.

The AIX fixes can be downloaded via https from:

<https://aix.software.ibm.com/aix/efixes/security/curl_fix5.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.

Please reference the Affected Products and Version section above for help with checking installed fileset levels.

To extract the fixes from the tar file:

tar xvf curl_fix5.tar

cd curl_fix5

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/curl_advisory5.asc.sig&gt;

B. 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:

<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