AIX is vulnerable to arbitrary command execution due to invscout

IBM SECURITY ADVISORY

First Issued: Wed Apr 12 12:32:10 CDT 2023

The most recent version of this document is available here:
https://aix.software.ibm.com/aix/efixes/security/invscout_advisory4.asc

Security Bulletin: AIX is vulnerable to arbitrary command execution due to
invscout (CVE-2023-28528)

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

SUMMARY:

A vulnerability in the AIX invscout command could allow a non-privileged
local user to execute arbitrary commands (CVE-2023-28528).

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

VULNERABILITY DETAILS:

CVEID: CVE-2023-28528
    https://vulners.com/cve/CVE-2023-28528
DESCRIPTION: IBM AIX could allow a non-privileged local user to exploit a
    vulnerability in the invscout command to execute arbitrary commands.
CVSS Base Score: 8.4
CVSS Temporal Score: See 
    https://exchange.xforce.ibmcloud.com/vulnerabilities/251207
    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 following fileset levels are vulnerable:
    
    key_fileset = aix

    Fileset                 Lower Level  Upper Level KEY 
    ---------------------------------------------------------
    invscout.rte            2.2.0.0      2.2.0.23    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 invscout.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 https from:

        https://aix.software.ibm.com/aix/efixes/security/invscout_fix4.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 AIX 7.1, 7.2, and VIOS 3.1, you must be on the 'bos.rte.libc
        prereq' level before installing the new invscout.rte package.

        AIX Level      bos.rte.libc prereq
        ----------------------------------
        7.1            7.1.5.30
        7.2            7.2.3.0

        VIOS Level     bos.rte.libc prereq 
        ----------------------------------
        3.1            7.2.3.0

        To extract the fixes from the tar file:

        tar xvf invscout_fix4.tar
        cd invscout_fix4

        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
        -----------------------------------------------------------------------------------------------------
        f13845513b60d3df0699a30fa1c328079983a35ae4b6cfa6db4e4d571b2d530c  invscout.rte             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/invscout_advisory4.asc.sig

    B. 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 the fix installation:

        installp -apYd . invscout

        To install the fix package:

        installp -aXYd . invscout


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:

    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 due
    to invscout (CVE-2023-28528)
    https://www.ibm.com/support/pages/node/6983232

ACKNOWLEDGEMENTS:

None.

CHANGE HISTORY:

First Issued: Wed Apr 12 12:32:10 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
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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.