AIX is vulnerable to a denial of service due to libxml2

IBM SECURITY ADVISORY

First Issued: Tue Jul 25 11:08:32 CDT 2023

The most recent version of this document is available here:
https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory5.asc

Security Bulletin: AIX is vulnerable to a denial of service due to libxml2
(CVE-2023-29469 and CVE-2023-28484)

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

SUMMARY:

Vulnerabilities in libxml2 could allow a remote attacker to cause a
denial of service (CVE-2023-29469 and CVE-2023-28484). AIX uses libxml2 as 
part of its XML parsing functions.

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

VULNERABILITY DETAILS:

CVEID: CVE-2023-29469
    https://vulners.com/cve/CVE-2023-29469
DESCRIPTION: GNOME libxml2 is vulnerable to a denial of service, caused by
    a double free flaw in the xmlDictComputeFastKey function due to
    hashing empty strings are not null-terminated. By persuading a victim
    to open a specially crafted XML content, a remote attacker could
    exploit this vulnerability to cause a denial of service condition.
CVSS Base Score: 5.5
CVSS Temporal Score: See 
    https://exchange.xforce.ibmcloud.com/vulnerabilities/253143
    for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)

CVEID: CVE-2023-28484
    https://vulners.com/cve/CVE-2023-28484
DESCRIPTION: GNOME libxml2 is vulnerable to a denial of service, caused by
    a NULL pointer dereference flaw in the xmlSchemaFixupComplexType
    function. By persuading a victim to open a specially crafted XML
    content, a remote attacker could exploit this vulnerability to cause a
    denial of service condition.
CVSS Base Score: 5.5
CVSS Temporal Score: See
    https://exchange.xforce.ibmcloud.com/vulnerabilities/253138
    for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)


AFFECTED PRODUCTS AND VERSIONS:

    AIX 7.2, 7.3
    VIOS 3.1

    The following fileset levels are vulnerable:
    
    key_fileset = aix

    Fileset                 Lower Level  Upper Level KEY 
    ---------------------------------------------------------
    bos.rte.control         7.2.5.0      7.2.5.6     key_w_fs
    bos.rte.control         7.2.5.100    7.2.5.103   key_w_fs
    bos.rte.control         7.2.5.200    7.2.5.201   key_w_fs
    bos.rte.control         7.3.0.0      7.3.0.3     key_w_fs
    bos.rte.control         7.3.1.0      7.3.1.1     key_w_fs
    
    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 bos.rte.control


REMEDIATION:

    A. APARS
        
        IBM has assigned the following APARs to this problem:

        AIX Level APAR     Availability  SP        KEY
        -----------------------------------------------------
        7.2.5     IJ47597  **            SP07      key_w_apar
        7.3.0     IJ47629  **            N/A       key_w_apar
        7.3.1     IJ47630  **            SP03      key_w_apar

        VIOS Level APAR    Availability  SP        KEY
        -----------------------------------------------------
        3.1.2      IJ47631 **            N/A       key_w_apar
        3.1.3      IJ47632 **            3.1.3.50  key_w_apar
        3.1.4      IJ47597 **            3.1.4.30  key_w_apar

        Subscribe to the APARs here:

        https://www.ibm.com/support/pages/apar/IJ47597
        https://www.ibm.com/support/pages/apar/IJ47629
        https://www.ibm.com/support/pages/apar/IJ47630
        https://www.ibm.com/support/pages/apar/IJ47631
        https://www.ibm.com/support/pages/apar/IJ47632

        By subscribing, you will receive periodic email alerting you
        to the status of the APAR, and a link to download the fix once
        it becomes available.

    B. FIXES

        IBM strongly recommends addressing the vulnerability now.

        AIX and VIOS fixes are available. The fixes are cumulative and
        address previously issued AIX/VIOS libxml2 security bulletins with
        respect to SP and TL:
        https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory4.asc
        https://www.ibm.com/support/pages/node/6953825
        https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory3.asc
        https://www.ibm.com/support/pages/node/6619729


        The AIX and VIOS fixes can be downloaded via ftp or http from:

        https://aix.software.ibm.com/aix/efixes/security/libxml2_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
        ----------------------------------------------
        7.2.5.4    IJ47597m4a.230718.epkg.Z  key_w_fix
        7.2.5.5    IJ47597m6a.230717.epkg.Z  key_w_fix
        7.2.5.6    IJ47597m6a.230717.epkg.Z  key_w_fix
        7.3.0.2    IJ47629m4a.230718.epkg.Z  key_w_fix
        7.3.0.3    IJ47629m4a.230718.epkg.Z  key_w_fix
        7.3.0.4    IJ47629m4a.230718.epkg.Z  key_w_fix
        7.3.1.1    IJ47630m2a.230718.epkg.Z  key_w_fix
        7.3.1.2    IJ47630m2a.230718.epkg.Z  key_w_fix

        Please note that the above table refers to AIX TL/SP level as
        opposed to fileset level, i.e., 7.3.0.3 is AIX 7300-00-03.

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

        VIOS Level  Interim Fix (*.Z)         KEY
        -----------------------------------------------
        3.1.2.40    IJ47631m6a.230718.epkg.Z  key_w_fix
        3.1.2.50    IJ47631m6a.230718.epkg.Z  key_w_fix
        3.1.2.60    IJ47631m6a.230718.epkg.Z  key_w_fix
        3.1.3.21    IJ47632m4a.230718.epkg.Z  key_w_fix
        3.1.3.30    IJ47632m4a.230718.epkg.Z  key_w_fix
        3.1.3.40    IJ47632m4a.230718.epkg.Z  key_w_fix
        3.1.4.10    IJ47597m6a.230717.epkg.Z  key_w_fix
        3.1.4.21    IJ47597m6a.230717.epkg.Z  key_w_fix

        To extract the fixes from the tar file:

        tar xvf libxml2_fix5.tar
        cd libxml2_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
        -----------------------------------------------------------------------------------------------------
        3d2d1242eb42fadb11d1c3e9625a81bdf3f605a465039b7592d46ab401e68af7  IJ47597m4a.230718.epkg.Z key_w_csum
        c06c96eeae459c2533b0d2df958f31aafbcc6c274a732324039328ee7a272f97  IJ47597m6a.230717.epkg.Z key_w_csum
        b80ac199295a15227b8e946ff5db42324e62e40bbfbb59d81f5b2627286e505b  IJ47629m4a.230718.epkg.Z key_w_csum
        85b4de5a3bd7098cb808f48a9ceb40f3aefddae418e902f42691f68882d850c8  IJ47630m2a.230718.epkg.Z key_w_csum
        a72eb5c8c9012a0a3d9b4789b257e29740720f4a1948c2971d6dafd77ecccadc  IJ47631m6a.230718.epkg.Z key_w_csum
        38539a5de0ac8961a32bb5e872a79d4bee66b5de6735c9f049f2decc6dac581c  IJ47632m4a.230718.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/libxml2_advisory5.asc.sig

    C. 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:

        http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html

        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:

ftp://ftp.software.ibm.com/systems/power/AIX/systems_p_os_aix_security_pubkey.txt
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/libxml2_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 a denial of service due to
    libxml2 (CVE-2023-29469 and CVE-2023-28484)
    https://www.ibm.com/support/pages/node/7014485

ACKNOWLEDGEMENTS:

None.

CHANGE HISTORY:

First Issued: Tue Jul 25 11:08:32 CDT 2023

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

*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.