AIX is vulnerable to security restrictions bypass due to cURL libcurl (CVE-2024-0853)

IBM SECURITY ADVISORY

First Issued: Thu Jun 20 15:10:42 CDT 2024

The most recent version of this document is available here:
https://aix.software.ibm.com/aix/efixes/security/curl_advisory5.asc

Security Bulletin: AIX is vulnerable to security restrictions bypass due to
cURL libcurl (CVE-2024-0853)

===============================================================================

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
    https://vulners.com/cve/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 Environmental Score*: Undefined
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:

    AIX 7.3 TL1 SP4, 7.3 TL2 SP2

    The following fileset levels are vulnerable:
    
    key_fileset = aix

    Fileset                 Lower Level  Upper Level KEY 
    ---------------------------------------------------------
    oss.lib.libcurl         8.5.0.0      8.5.0.0     key_w_fs

    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:

    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 

        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.

        AIX Level         Interim Fix (*.Z)        KEY
        ----------------------------------------------------
        7.3.1.4, 7.3.2.2  853sa.240503.epkg.Z      key_w_fix

        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:

        openssl dgst -sha256                                              filename                 KEY
        -----------------------------------------------------------------------------------------------------
        77bc027152c49e7c572858fc7ada4183f2a556ef846ee0e26fc9e47ba4c9aaa4  853sa.240503.epkg.Z      key_w_csum

        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/ 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

    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

        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.

===============================================================================

CONTACT US:

Note: Keywords labeled as KEY in this document are used for parsing
purposes.

If you would like to receive AIX Security Advisories via email,
please visit "My Notifications":

    http://www.ibm.com/support/mynotifications

Contact IBM Support for questions related to this announcement:

    https://ibm.com/support/

For information on how to securely verify AIX security bulletins and fixes:

    https://www.ibm.com/support/pages/node/6985269

To obtain the OpenSSL public key that can be used to verify the
signed advisories and ifixes:

    Download the key from our web page:

https://aix.software.ibm.com/aix/efixes/security/systems_p_os_aix_security_pubkey.txt

To verify the AIX/VIOS security bulletin:

    Published advisory OpenSSL signature file location:

    https://aix.software.ibm.com/aix/efixes/security/curl_advisory5.asc.sig

    openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]

Please contact your local IBM AIX support center for any
assistance.

REFERENCES:

Complete CVSS v3 Guide:  http://www.first.org/cvss/user-guide
On-line Calculator v3:
    http://www.first.org/cvss/calculator/3.0

RELATED INFORMATION:

IBM Secure Engineering Web Portal
    http://www.ibm.com/security/secure-engineering/bulletins.html

IBM Product Security Incident Response Blog
    https://www.ibm.com/blogs/psirt/

Security Bulletin: AIX is vulnerable to security restrictions bypass due
    to cURL libcurl (CVE-2024-0853)
    https://www.ibm.com/support/pages/node/7158221

ACKNOWLEDGEMENTS:

None.

CHANGE HISTORY:

First Issued: Thu Jun 20 15:10:42 CDT 2024

===============================================================================

*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
According to the Forum of Incident Response and Security Teams (FIRST), the
Common Vulnerability Scoring System (CVSS) is an “industry open standard
designed to convey vulnerability severity and help to determine urgency and
priority of response.” IBM PROVIDES THE CVSS SCORES “AS IS” WITHOUT WARRANTY
OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT
OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.