AIX is vulnerable to arbitrary command execution

IBM SECURITY ADVISORY

First Issued: Wed Apr 12 12:36:51 CDT 2023

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

Security Bulletin: AIX is vulnerable to arbitrary command execution
(CVE-2023-26286)

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

SUMMARY:

A vulnerability in the AIX runtime services library could allow a
non-privileged local user to execute arbitrary commands (CVE-2023-26286).

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

VULNERABILITY DETAILS:

CVEID: CVE-2023-26286
    https://vulners.com/cve/CVE-2023-26286
DESCRIPTION: IBM AIX could allow a non-privileged local user to exploit a
    vulnerability in the AIX runtime services library to execute
    arbitrary commands.
CVSS Base Score: 8.4
CVSS Temporal Score: See 
    https://exchange.xforce.ibmcloud.com/vulnerabilities/248421
    for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)


AFFECTED PRODUCTS AND VERSIONS:

    AIX 7.1, 7.2, 7.3
    VIOS 3.1

    The vulnerabilities in the following filesets are being addressed:
    
    key_fileset = aix

    Fileset                 Lower Level  Upper Level KEY 
    ---------------------------------------------------------
    bos.mp64                7.1.5.0      7.1.5.47    key_w_fs
    bos.rte.serv_aid        7.1.5.0      7.1.5.36    key_w_fs
    bos.mp64                7.2.5.0      7.2.5.6     key_w_fs
    bos.rte.serv_aid        7.2.5.0      7.2.5.4     key_w_fs
    bos.sysmgt.serv_aid     7.2.5.0      7.2.5.3     key_w_fs
    bos.mp64                7.2.5.100    7.2.5.106   key_w_fs
    bos.rte.serv_aid        7.2.5.100    7.2.5.102   key_w_fs
    bos.sysmgt.serv_aid     7.2.5.100    7.2.5.102   key_w_fs
    bos.mp64                7.2.5.200    7.2.5.201   key_w_fs
    bos.rte.serv_aid        7.2.5.200    7.2.5.200   key_w_fs
    bos.sysmgt.serv_aid     7.2.5.200    7.2.5.200   key_w_fs
    bos.mp64                7.3.0.0      7.3.0.4     key_w_fs
    bos.rte.serv_aid        7.3.0.0      7.3.0.2     key_w_fs
    bos.sysmgt.serv_aid     7.3.0.0      7.3.0.1     key_w_fs
    bos.mp64                7.3.1.0      7.3.1.1     key_w_fs
    bos.rte.serv_aid        7.3.1.0      7.3.1.1     key_w_fs
    bos.sysmgt.serv_aid     7.3.1.0      7.3.1.0     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.mp64


REMEDIATION:

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

        AIX Level APAR     Availability  SP        KEY
        -----------------------------------------------------
        7.1.5     IJ45981  **            SP12      key_w_apar
        7.2.5     IJ45245  **            SP06      key_w_apar
        7.3.0     IJ45997  **            SP04      key_w_apar
        7.3.1     IJ45246  **            SP02      key_w_apar

        VIOS Level APAR    Availability  SP        KEY
        -----------------------------------------------------
        3.1.2      IJ46110 **            3.1.2.60  key_w_apar
        3.1.3      IJ46051 **            3.1.3.40  key_w_apar
        3.1.4      IJ45245 **            3.1.4.20  key_w_apar

        Subscribe to the APARs here:

        https://www.ibm.com/support/pages/apar/[APAR Number]

        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 https from:

        https://aix.software.ibm.com/aix/efixes/security/librts_fix.tar 

        The AIX error daemon, errdemon, should be stopped and restarted
        after iFix installation to complete the install:

        # /usr/lib/errstop
        # /usr/lib/errdemon

        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
        ----------------------------------------------
        7.1.5.9    IJ45981s9a.230324.epkg.Z  key_w_fix
        7.1.5.10   IJ45981sAa.230323.epkg.Z  key_w_fix
        7.1.5.11   IJ45981sBa.230407.epkg.Z  key_w_fix
        7.2.5.3    IJ45245s3a.230324.epkg.Z  key_w_fix
        7.2.5.4    IJ45245s4a.230324.epkg.Z  key_w_fix
        7.2.5.5    IJ45245s5a.230322.epkg.Z  key_w_fix
        7.3.0.1    IJ45997s1a.230322.epkg.Z  key_w_fix
        7.3.0.2    IJ45997s2a.230322.epkg.Z  key_w_fix
        7.3.0.3    IJ45997s3a.230322.epkg.Z  key_w_fix
        7.3.1.1    IJ45246s1a.230322.epkg.Z  key_w_fix

        Please note that the above table refers to AIX TL/SP level as
        opposed to fileset level, i.e., 7.2.5.4 is AIX 7200-05-04.

        VIOS Level  Interim Fix (*.Z)         KEY
        --------------------------------------------
        3.1.2.30    IJ46110s3a.230323.epkg.Z  key_w_fix
        3.1.2.40    IJ46110s4a.230323.epkg.Z  key_w_fix
        3.1.2.50    IJ46110s5a.230407.epkg.Z  key_w_fix
        3.1.3.14    IJ46051s1a.230323.epkg.Z  key_w_fix
        3.1.3.21    IJ46051s2a.230323.epkg.Z  key_w_fix
        3.1.3.30    IJ46051s3a.230323.epkg.Z  key_w_fix
        3.1.4.10    IJ45245s5a.230322.epkg.Z  key_w_fix


        To extract the fixes from the tar file:

        tar xvf librts_fix.tar
        cd librts_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
        -----------------------------------------------------------------------------------------------------
        b2ce7cf6aed5e9e325a9babf29e950f5d0aef394da305e32ad54bd8af13a04f8  IJ45245s3a.230324.epkg.Z key_w_csum
        f1729e6086bdab6669cd45841707cb398acbf0acbacc351ac7e5ad67260ee713  IJ45245s4a.230324.epkg.Z key_w_csum
        60fe19af30c5e32f7a129b82cbcab606cd08236e73c0dcd968b5ab495fdd2476  IJ45245s5a.230322.epkg.Z key_w_csum
        016fcc1f02f1690d38d4558b4d9457271d2fc97320ead6e9af2164c1036ff5a9  IJ45246s1a.230322.epkg.Z key_w_csum
        c0fae4d17e285bf82780de8dde66b98f92d41d3b3e556888dd3f45e46d33b96b  IJ45981sAa.230323.epkg.Z key_w_csum
        c789fbd38fb99cc00c67dad1593d7db9d6e9442be366e1a7b7052551d58e88b1  IJ45981sBa.230407.epkg.Z key_w_csum
        8d065f161451d2c4610cfc9efc2784e6bba7f4d2edb6687d31fd1a46b8358a40  IJ45981s9a.230324.epkg.Z key_w_csum
        5f51f7577ef77d0e67d06da73992c8b425d369de935c54c87e10ad57b7d0c8d9  IJ45997s1a.230322.epkg.Z key_w_csum
        24f05177f32ef54b38eb0649cfc51a64e3c548b69382dbe35fea8ffa7ce7f291  IJ45997s2a.230322.epkg.Z key_w_csum
        a3df21e1d61dfa3763cb5961e202aedd4b57506afd13a5e089f77cfb6f4cc83c  IJ45997s3a.230322.epkg.Z key_w_csum
        7de35cba53f8f092c6aeeb545dad69dbea85855044480205c0eb1298065e013e  IJ46051s1a.230323.epkg.Z key_w_csum
        356e002d20e36ddc4814ebb1517826eafca3cfab3434f4d47892665a21d7da5a  IJ46051s2a.230323.epkg.Z key_w_csum
        5673b7e749d7bada523a2d3917fe03a3cb69025ebb10c8080be8f53a7b8db761  IJ46051s3a.230323.epkg.Z key_w_csum
        e3465d874ddfbb283c4a4985f77f7f777beb63a273d3704f9fb663a94f1ae1e1  IJ46110s3a.230323.epkg.Z key_w_csum
        2badfd45477c32a71378f3e61f0b887ae19a50e588e6a18b9c5c99694af09b9c  IJ46110s4a.230323.epkg.Z key_w_csum
        f36c500647ce64a4ed9b5ad2bde3c09db4f98007781921982b84cde7551a2d8b  IJ46110s5a.230407.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/librts_advisory.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/

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 arbitrary command execution
        (CVE-2023-26286)
    https://www.ibm.com/support/pages/node/6983236

ACKNOWLEDGEMENTS:

None.

CHANGE HISTORY:

First Issued: Wed Apr 12 12:36:51 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.