AIX is vulnerable to denial of service due to zlib and zlibNX

IBM SECURITY ADVISORY

First Issued: Wed Sep 28 13:38:50 CDT 2022

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

Security Bulletin: AIX is vulnerable to denial of service due to zlib
and zlibNX (CVE-2018-25032)

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

SUMMARY:

A vulnerability in zlib and zlibNX could allow a remote attacker to cause
a denial of service (CVE-2018-25032). AIX uses zlib and zlibNX as part 
of its data compression functions.

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

VULNERABILITY DETAILS:

CVEID: CVE-2018-25032
    https://vulners.com/cve/CVE-2018-25032
    https://vulners.com/cve/CVE-2018-25032
DESCRIPTION: Zlib is vulnerable to a denial of service, caused by a
    memory corruption in the deflate operation. By using many distant
    matches, a remote attacker could exploit this vulnerability to cause
    the application to crash.
CVSS Base Score: 7.5
CVSS Temporal Score: See 
    https://exchange.xforce.ibmcloud.com/vulnerabilities/222615
    for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)


AFFECTED PRODUCTS AND VERSIONS:

    AIX 7.1, 7.2, 7.3
    VIOS 3.1

    The following fileset levels are vulnerable:
    
    key_fileset = aix

    For zlib:

    Fileset                 Lower Level  Upper Level KEY       PRODUCT(S)
    ---------------------------------------------------------------------
    rpm.rte                 4.9.1.3      4.15.1.1005 key_w_fs  zlib
    rpm.rte                 4.15.1.2000  4.15.1.2005 key_w_fs  zlib

    For zlibNX:

    Fileset                 Lower Level  Upper Level KEY       PRODUCT(S)
    ---------------------------------------------------------------------
    zlibNX.rte              7.2.4.0      7.2.4.7     key_w_fs  zlibNX
    zlibNX.rte              7.3.0.0      7.3.0.1     key_w_fs  zlibNX

    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 zlibNX.rte


REMEDIATION:

    A. FIXES

        IBM strongly recommends addressing the vulnerability now.

        AIX and VIOS fixes are available.

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

        ftp://aix.software.ibm.com/aix/efixes/security/zlib_fix.tar
        http://aix.software.ibm.com/aix/efixes/security/zlib_fix.tar
        https://aix.software.ibm.com/aix/efixes/security/zlib_fix.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.

        For zlib:

        AIX Level       Fix                       KEY        PRODUCT(S)
        ---------------------------------------------------------------
        7.1, 7.2        rpm.rte.4.15.1.1006       key_w_fix  zlib
        7.3             rpm.rte.4.15.1.2006       key_w_fix  zlib

        VIOS Level      Fix                       KEY        PRODUCT(S)
        ---------------------------------------------------------------
        3.1             rpm.rte.4.15.1.1006       key_w_fix  zlib


        For zlibNX:

        AIX Level  Interim Fix (*.Z)         KEY        PRODUCT(S)
        ----------------------------------------------------------
        7.2        IJ41754s4a.220829.epkg.Z  key_w_fix  zlibNX
        7.3        IJ42198s2a.220829.epkg.Z  key_w_fix  zlibNX

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

        VIOS Level  Interim Fix (*.Z)         KEY        PRODUCT(S)
        -----------------------------------------------------------
        3.1         IJ41754s4a.220829.epkg.Z  key_w_fix  zlibNX


        To extract the fixes from the tar file:

        tar xvf zlib_fix.tar
        cd zlib_fix

        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
        -----------------------------------------------------------------------------------------------------
        6e830be2ce0057d12072bef887337b39a5fb97cc6fceafbdf3c9d1c8f6bda8be  IJ41754s4a.220829.epkg.Z key_w_csum
        91b35e4f334463f49d76e263c70fa8dce09dbc9825d3bb7640b8d186511dfd02  IJ42198s2a.220829.epkg.Z key_w_csum
        f12ab2fa1cce9129dc27f2d8a6af1f3e5a1075c93da87ff5f67519d19cfd8db1  rpm.rte.4.15.1.1006 key_w_csum
        942c99ecb388645676e3f9361b0157406997188f4249ff7d07ee58bf3271cc34  rpm.rte.4.15.1.2006 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:

        http://aix.software.ibm.com/aix/efixes/security/zlib_advisory.asc.sig
        https://aix.software.ibm.com/aix/efixes/security/zlib_advisory.asc.sig
        ftp://aix.software.ibm.com/aix/efixes/security/zlib_advisory.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:

        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.

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Contact IBM Support for questions related to this announcement:

    http://ibm.com/support/
    https://ibm.com/support/

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

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 denial of service due to zlib
    and zlibNX (CVE-2018-25032)
    https://www.ibm.com/support/pages/node/6824891

ACKNOWLEDGEMENTS:

None.

CHANGE HISTORY:

First Issued: Wed Sep 28 13:38:50 CDT 2022

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

*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.