AIX is vulnerable to cache poisoning due to ISC BIND

IBM SECURITY ADVISORY

First Issued: Thu Jul 28 13:24:22 CDT 2022

The most recent version of this document is available here:
http://aix.software.ibm.com/aix/efixes/security/bind_advisory21.asc
https://aix.software.ibm.com/aix/efixes/security/bind_advisory21.asc
ftp://aix.software.ibm.com/aix/efixes/security/bind_advisory21.asc

Security Bulletin: AIX is vulnerable to cache poisoning due to ISC BIND
(CVE-2021-25220)

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

SUMMARY:

A vulnerability in ISC BIND could allow a remote attacker to poison the 
cache (CVE-2021-25220). AIX uses ISC BIND as part of its DNS functions.

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

VULNERABILITY DETAILS:

CVEID: CVE-2021-25220
    https://vulners.com/cve/CVE-2021-25220
    https://vulners.com/cve/CVE-2021-25220
DESCRIPTION: ISC BIND could allow a remote attacker to bypass security
    restrictions, caused by an error when using DNS forwarders. An
    attacker could exploit this vulnerability to poison the cache with
    incorrect records leading to queries being made to the wrong servers,
    which might also result in false information being returned to
    clients.
CVSS Base Score: 6.8
CVSS Temporal Score: See 
    https://exchange.xforce.ibmcloud.com/vulnerabilities/221991
    for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N)


AFFECTED PRODUCTS AND VERSIONS:

    AIX 7.1, 7.2, 7.3
    VIOS 3.1

    The following fileset levels are vulnerable:
    
    key_fileset = aix

    Fileset                 Lower Level  Upper Level KEY 
    ---------------------------------------------------------
    bos.net.tcp.server      7.1.5.0      7.1.5.35    key_w_fs
    bos.net.tcp.client      7.1.5.0      7.1.5.40    key_w_fs
    bos.net.tcp.bind_utils  7.2.4.0      7.2.4.3     key_w_fs
    bos.net.tcp.bind_utils  7.2.5.0      7.2.5.2     key_w_fs
    bos.net.tcp.bind_utils  7.2.5.100    7.2.5.101   key_w_fs
    bos.net.tcp.bind_utils  7.3.0.0      7.3.0.1     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.net.tcp.server


REMEDIATION:

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

        AIX Level APAR     Availability  SP        KEY
        -----------------------------------------------------
        7.1.5     IJ40617  **            SP11      key_w_apar
        7.2.4     IJ40616  **            N/A       key_w_apar
        7.2.5     IJ40674  **            SP05      key_w_apar
        7.3.0     IJ40614  **            SP03      key_w_apar

        VIOS Level APAR    Availability  SP        KEY
        -----------------------------------------------------
        3.1.1      IJ40616 **            N/A       key_w_apar
        3.1.2      IJ40615 **            3.1.2.40  key_w_apar
        3.1.3      IJ41139 **            3.1.3.30  key_w_apar

        Subscribe to the APARs here:

        http://www.ibm.com/support/pages/apar/IJ40614
        http://www.ibm.com/support/pages/apar/IJ40615
        http://www.ibm.com/support/pages/apar/IJ40616
        http://www.ibm.com/support/pages/apar/IJ40617
        http://www.ibm.com/support/pages/apar/IJ40674
        http://www.ibm.com/support/pages/apar/IJ41139

        https://www.ibm.com/support/pages/apar/IJ40614
        https://www.ibm.com/support/pages/apar/IJ40615
        https://www.ibm.com/support/pages/apar/IJ40616
        https://www.ibm.com/support/pages/apar/IJ40617
        https://www.ibm.com/support/pages/apar/IJ40674
        https://www.ibm.com/support/pages/apar/IJ41139

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

        ftp://aix.software.ibm.com/aix/efixes/security/bind_fix21.tar
        http://aix.software.ibm.com/aix/efixes/security/bind_fix21.tar
        https://aix.software.ibm.com/aix/efixes/security/bind_fix21.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
        ----------------------------------------------
        7.1.5.7    IJ40617m9b.220718.epkg.Z  key_w_fix
        7.1.5.8    IJ40617m9b.220718.epkg.Z  key_w_fix
        7.1.5.9    IJ40617m9b.220718.epkg.Z  key_w_fix
        7.2.4.3    IJ40616m5b.220718.epkg.Z  key_w_fix
        7.2.4.4    IJ40616m5b.220718.epkg.Z  key_w_fix
        7.2.4.5    IJ40616m5b.220718.epkg.Z  key_w_fix
        7.2.5.2    IJ40615m4b.220718.epkg.Z  key_w_fix
        7.2.5.3    IJ40615m4b.220718.epkg.Z  key_w_fix
        7.2.5.4    IJ40615m4b.220718.epkg.Z  key_w_fix
        7.3.0.1    IJ40614m2b.220718.epkg.Z  key_w_fix
        7.3.0.2    IJ40614m2b.220718.epkg.Z  key_w_fix

        Please note that the above table refers to AIX TL/SP level as
        opposed to fileset level, i.e., 7.2.5.2 is AIX 7200-05-02.

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

        VIOS Level  Interim Fix (*.Z)         KEY
        -----------------------------------------------
        3.1.1.30    IJ40616m5b.220718.epkg.Z  key_w_fix
        3.1.1.40    IJ40616m5b.220718.epkg.Z  key_w_fix
        3.1.1.50    IJ40616m5b.220718.epkg.Z  key_w_fix
        3.1.2.10    IJ40615m4b.220718.epkg.Z  key_w_fix
        3.1.2.21    IJ40615m4b.220718.epkg.Z  key_w_fix
        3.1.3.10    IJ40615m4b.220718.epkg.Z  key_w_fix
        3.1.3.14    IJ40615m4b.220718.epkg.Z  key_w_fix
        3.1.3.21    IJ40615m4b.220718.epkg.Z  key_w_fix

        The above fixes are cumulative and address previously issued
        AIX/VIOS BIND security bulletins.

        To extract the fixes from the tar file:

        tar xvf bind_fix21.tar
        cd bind_fix21

        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
        -----------------------------------------------------------------------------------------------------
        6c62ac5b0598ac3117445cfc5797aa6b85c4f527572e32d31d147849803b61ce  IJ40614m2b.220718.epkg.Z key_w_csum
        93bcac519d552563e6b4fa1f74712c6acf2b0c218d59be98dd1d8ad2cfcf3b21  IJ40615m4b.220718.epkg.Z key_w_csum
        33b06edaae5964176f6c6d7ea58a97d2dbd142ee0817f56b16bcbb03b9a500d4  IJ40616m5b.220718.epkg.Z key_w_csum
        199c9caa64e4fac6822e7ea11bde174cfddaaf00deb8ac294d86b9e512aed418  IJ40617m9b.220718.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:

        http://aix.software.ibm.com/aix/efixes/security/bind_advisory21.asc.sig
        https://aix.software.ibm.com/aix/efixes/security/bind_advisory21.asc.sig
        ftp://aix.software.ibm.com/aix/efixes/security/bind_advisory21.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":

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To view previously issued advisories, please visit:

    http://www14.software.ibm.com/webapp/set2/subscriptions/onvdq

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 cache poisoning due to ISC BIND
    (CVE-2021-25220)
    https://www.ibm.com/support/pages/node/6607880

ACKNOWLEDGEMENTS:

None.

CHANGE HISTORY:

First Issued: Thu Jul 28 13:24:22 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.