There is a vulnerability in the AIX smbcd daemon.

IBM SECURITY ADVISORY

First Issued: Thu Feb 24 14:37:23 CST 2022

The most recent version of this document is available here:

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

Security Bulletin: Vulnerability in the AIX smbcd daemon (CVE-2021-38993)

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

SUMMARY:

There is a vulnerability in the AIX smbcd daemon.

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

VULNERABILITY DETAILS:

CVEID: CVE-2021-38993
    https://vulners.com/cve/CVE-2021-38993
    https://vulners.com/cve/CVE-2021-38993
DESCRIPTION: IBM AIX could allow a non-privileged local user to exploit a
    vulnerability in the smbcd daemon to cause a denial of service.
CVSS Base Score: 6.2
CVSS Temporal Score: See
    https://exchange.xforce.ibmcloud.com/vulnerabilities/212962
    for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:L/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 = osrcaix

    Fileset                 Lower Level   Upper Level    KEY
    -------------------------------------------------------------
    smbc.rte                7.1.0.0       7.1.302.6      key_w_fs
    smbc.rte                7.2.0.0       7.2.302.6      key_w_fs

    To determine if your system is vulnerable, execute the
    following commands:

    lslpp -L | grep -i smbc.rte

REMEDIATION:

    FIXES

        The fixes can be downloaded via ftp or http from:

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

        The latest SMB client fileset may also be downloaded from:
        https://www.ibm.com/resources/mrs/assets?source=aixbp

        To extract the fixes from the tar file:

        For AIX 7.1:
        tar xvf smbcd_fix.tar
        gunzip smbc_302_fileset_71.tar.gz | tar xvf

        For AIX 7.2, 7.3, and VIOS 3.1:
        tar xvf smbcd_fix.tar
        gunzip smbc_302_fileset_72.tar.gz | tar xvf

        IMPORTANT: 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 the fix installation:

        installp -apYd . smbc

        To install the fix package:

        installp -aXYd . smbc

        Verify you have retrieved the fixes intact:

        The checksums below were generated using the
        "openssl dgst -sha256 [file]" command as the following:

        openssl dgst -sha256                                              filename                   KEY
        -------------------------------------------------------------------------------------------------------
        82386d9913a386c234dcef6bafa53c803d173760218cea34b94645ab18a89f1f  smbc_302_fileset_71.tar.gz key_w_csum
        ee3966422b87e95b3cdba9537f6276c8e48be9d89ca409fbd258c2a20230034b  smbc_302_fileset_72.tar.gz 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 AIX Support at
        https://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 [fix_file].sig [fix_file]

        Published advisory OpenSSL signature file location:

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


WORKAROUNDS AND MITIGATIONS:

    None.

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

CONTACT US:

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

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

RELATED INFORMATION:

Security Bulletin: Vulnerabilities in the AIX smbcd daemon (CVE-2021-38993)
    https://www.ibm.com/support/pages/node/6559320

ACKNOWLEDGEMENTS:

None.

CHANGE HISTORY:

First Issued: Thu Feb 24 14:37:23 CST 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.