Security Bulletin
Summary
There is a vulnerability in the gencore user command that affects AIX.
Vulnerability Details
CVEID: CVE-2020-4887
DESCRIPTION: IBM AIX could allow a local user to exploit a vulnerability in the gencore user command to create arbitrary files in any directory.
CVSS Base score: 6.2
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/190911 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N)
DESCRIPTION: IBM AIX could allow a local user to exploit a vulnerability in the gencore user command to create arbitrary files in any directory.
CVSS Base score: 6.2
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/190911 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| AIX | 7.1 |
| AIX | 7.2 |
| VIOS | 3.1 |
The vulnerabilities in the following filesets are being addressed:
| Fileset | Lower Level | Upper Level |
| bos.mp64 | 7.1.5.0 | 7.1.5.40 |
| bos.mp64 | 7.2.3.0 | 7.2.3.19 |
| bos.mp64 | 7.2.4.0 | 7.2.4.7 |
| bos.mp64 | 7.2.5.0 | 7.2.5.1 |
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/Fixes
A. APARS
IBM has assigned the following APARs to this problem:
| AIX Level | APAR | SP |
| 7.1.5 | IJ28825 | SP08 |
| 7.2.3 | IJ28826 | SP07 |
| 7.2.4 | IJ28827 | SP04 |
| 7.2.5 | IJ28828 | SP02 |
| VIOS Level | APAR | SP |
| 3.1.0 | IJ28826 | 3.1.0.60 |
| 3.1.1 | IJ28827 | 3.1.1.40 |
| 3.1.2 | IJ28828 | 3.1.2.20 |
Subscribe to the APARs here:
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
AIX and VIOS fixes are available.
An LPAR system reboot is required to complete the iFix installation, or Live Update may be used on AIX 7.2 to avoid a reboot.
The AIX and VIOS fixes can be downloaded via ftp or http from:
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) |
| 7.1.5.5 | IJ28825m5a.201221.epkg.Z |
| 7.1.5.5 | IJ28825m5b.201221.epkg.Z |
| 7.1.5.6 | IJ28825m6a.201221.epkg.Z |
| 7.1.5.6 | IJ28825m6b.201221.epkg.Z |
| 7.1.5.6 | IJ28825m6c.201221.epkg.Z |
| 7.1.5.7 | IJ28825m7a.201221.epkg.Z |
| 7.1.5.7 | IJ28825m7b.201221.epkg.Z |
| 7.2.3.3 | IJ28826m3a.201221.epkg.Z |
| 7.2.3.4 | IJ28826m4a.201221.epkg.Z |
| 7.2.3.5 | IJ28826m5a.201221.epkg.Z |
| 7.2.4.0 | IJ28827m0a.201222.epkg.Z |
| 7.2.4.1 | IJ28827m1a.201222.epkg.Z |
| 7.2.4.2 | IJ28827m2a.201222.epkg.Z |
| 7.2.4.2 | IJ28827m2b.201222.epkg.Z |
| 7.2.4.2 | IJ28827m2c.201222.epkg.Z |
| 7.2.4.3 | IJ28827m3a.210306.epkg.Z |
| 7.2.5.0 | IJ28828m1a.201222.epkg.Z |
| 7.2.5.1 | IJ28828m1a.201222.epkg.Z |
Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.2.3.5 is AIX 7200-03-05.
NOTE: Multiple iFixes are provided for AIX 7100-05-05, 7100-05-06, 7100-05-07, and 7200-04-02.
IJ28825m5a is for AIX 7100-05-05 with bos.mp64 fileset level 7.1.5.35.
IJ28825m5b is for AIX 7100-05-05 with bos.mp64 fileset level 7.1.5.34.
IJ28825m6a is for AIX 7100-05-06 with bos.mp64 fileset level 7.1.5.38.
IJ28825m6b is for AIX 7100-05-06 with bos.mp64 fileset level 7.1.5.37.
IJ28825m6c is for AIX 7100-05-06 with bos.mp64 fileset level 7.1.5.36.
IJ28825m7a is for AIX 7100-05-07 with bos.mp64 fileset level 7.1.5.40.
IJ28825m7b is for AIX 7100-05-07 with bos.mp64 fileset level 7.1.5.39.
IJ28827m2a is for AIX 7200-04-02 with bos.mp64 fileset level 7.2.4.6.
IJ28827m2b is for AIX 7200-04-02 with bos.mp64 fileset level 7.2.4.4.
IJ28827m2c is for AIX 7200-04-02 with bos.mp64 fileset level 7.2.4.3.
Please reference the Affected Products and Version section above for help with checking installed fileset levels.
| VIOS Level | Interim Fix (*.Z) |
| 3.1.0.20 | IJ28826m3a.201221.epkg.Z |
| 3.1.0.30 | IJ28826m4a.201221.epkg.Z |
| 3.1.0.40 | IJ28826m5a.201221.epkg.Z |
| 3.1.1.0 | IJ28827m0a.201222.epkg.Z |
| 3.1.1.10 | IJ28827m1b.201222.epkg.Z |
| 3.1.1.20 | IJ28827m2c.201222.epkg.Z |
| 3.1.1.21 | IJ28827m2b.201222.epkg.Z |
| 3.1.1.25 | IJ28827m2a.201222.epkg.Z |
| 3.1.1.30 | IJ28827m3a.210306.epkg.Z |
| 3.1.2.0 | IJ28828m1a.201222.epkg.Z |
| 3.1.2.10 | IJ28828m1a.201222.epkg.Z |
The fixes are cumulative and address previously issued AIX/VIOS kernel security bulletins with respect to SP and TL, which includes:
To extract the fixes from the tar file:
tar xvf gencore_fix.tar
cd gencore_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 |
| 6d8482ef0decc18eb9cb37820ba1b8099cdf158523b6a95006cee1a081a48f83 | IJ28825m5a.201221.epkg.Z |
| 343e07de2e256b5439851da18ba3ea3a21dca3a98b55cba09306d46145c952de | IJ28825m5b.201221.epkg.Z |
| 71c903ff543d5c583d74330a48fdd60ab52d82ff8214407237ca9b8929d38d27 | IJ28825m6a.201221.epkg.Z |
| e2798e2d78872870e153fad899b7f9b4c0eb0447b1068211050a91230989aa71 | IJ28825m6b.201221.epkg.Z |
| 3ac89e2e382cba3c440f37789f437a48be61f2bebcdf398e0a97ab2fa5dd20f7 | IJ28825m6c.201221.epkg.Z |
| 6bd374a44b0d571ce6628afb0ea163df493f942ddd618a616be24fa1839d7845 | IJ28825m7a.201221.epkg.Z |
| 0bce6ede7a2ea902d614eb892af533d90b4dfedf3a1d05f17b7ec1c21782fc38 | IJ28825m7b.201221.epkg.Z |
| ec4f01c8bc31b61f9679be6d03d3ed7ac9713a4349b31c855eaf4b0f4b9cf377 | IJ28826m3a.201221.epkg.Z |
| a3dae1d428ea866a7dab943285a4ebef8fa420451bd23bfeba919761fb4cd300 | IJ28826m4a.201221.epkg.Z |
| 8c6bb8caf628078c0387433ff978067280477d0b3ea3568102096cbf005a633c | IJ28826m5a.201221.epkg.Z |
| 5c9ad296cecb576dcef4631b75fa1987a9c856de07e466a5e1a6aa8529b7269f | IJ28827m0a.201222.epkg.Z |
| 8911ccd41e8926d247de9abc9da7387c1158a4b7606a945b2659dfaa95a6c8f6 | IJ28827m1a.201222.epkg.Z |
| e6b977bef6e2d799b5b0ad0fd0a03c3b59922ee0a76ccaf414db97ca879e1329 | IJ28827m1b.201222.epkg.Z |
| 0637ffbb60a918da32548c3861fbfa381db04be375cf21d372efdef3711ca569 | IJ28827m2a.201222.epkg.Z |
| 50786a721811b2eff98fbb24c85ed9bb8977f44891d29114d8fe43d79c0fe10e | IJ28827m2b.201222.epkg.Z |
| 4c6b71538dedded55aeffe7451a02998885dcc80ca12b1fa7937d53ff1a26402 | IJ28827m2c.201222.epkg.Z |
| 321cd8cf7362d25c05948b0717029e54bcc7233002a5eaae1b30d5e88d5b5f13 | IJ28827m3a.210306.epkg.Z |
| d8e107386c7eb45966ef9f3635f4e7253665c04795427f06a7e73a55b8847a54 | IJ28828m1a.201222.epkg.Z |
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 -sha1 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]
openssl dgst -sha1 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file]
Published advisory OpenSSL signature file location:
C. FIX AND INTERIM FIX INSTALLATION
An LPAR system reboot is required to complete the iFix installation, or Live Update may be used on AIX 7.2 to avoid a reboot.
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:
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
Get Notified about Future Security Bulletins
References
Off
Change History
19 Jan 2021: Initial Publication
30 March 2021: iFix now provided for AIX 7200-04-03 and VIOS 3.1.1.30
*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
Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.
Document Location
Worldwide
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Document Information
Modified date:
30 March 2021
UID
ibm16406022