Security Bulletin
Summary
There are vulnerabilities in OpenSSL used by AIX.
Vulnerability Details
CVEID: CVE-2021-23839
DESCRIPTION: OpenSSL could provide weaker than expected security, caused by incorrect SSLv2 rollback protection that allows for the inversion of the logic during a padding check. If the server is configured for SSLv2 support at compile time, configured for SSLv2 support at runtime or configured for SSLv2 ciphersuites, it will accept a connection if a version rollback attack has occurred and erroneously reject a connection if a normal SSLv2 connection attempt is made.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/196849 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N)
CVEID: CVE-2021-23840
DESCRIPTION: OpenSSL is vulnerable to a denial of service, caused by an integer overflow in CipherUpdate. By sending an overly long argument, an attacker could exploit this vulnerability to cause the application to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/196848 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2021-23841
DESCRIPTION: OpenSSL is vulnerable to a denial of service, caused by a NULL pointer dereference in the X509_issuer_and_serial_hash() function. By parsing the issuer field, an attacker could exploit this vulnerability to cause the application to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/196847 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| AIX | 7.1 |
| AIX | 7.2 |
| VIOS | 3.1 |
| Fileset | Lower Level | Upper Level |
| openssl.base | 1.0.2.500 | 1.0.2.2100 |
| openssl.base | 20.13.102.1000 | 20.16.102.2100 |
Remediation/Fixes
A. FIXES
The fixes can be downloaded via ftp or http from:
ftp://aix.software.ibm.com/aix/efixes/security/openssl_fix33.tar
http://aix.software.ibm.com/aix/efixes/security/openssl_fix33.tar
https://aix.software.ibm.com/aix/efixes/security/openssl_fix33.tar
The links above are 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.
Note that the tar file contains Interim fixes that are based on OpenSSL version, and AIX OpenSSL fixes are cumulative.
You must be on the 'prereq for installation' level before applying the interim fix. This may require installing a new level (prereq version) first.
| AIX Level | Interim Fix | Fileset Name (prereq for installation) |
| 7.1, 7.2 | 1022100b.210323.epkg.Z | openssl.base (1.0.2.2100) |
| 7.1, 7.2 | fips2100b.210323.epkg.Z | openssl.base (20.16.102.2100) |
| VIOS Level | Interim Fix | Fileset Name (prereq for installation) |
| 3.1 | 1022100b.210323.epkg.Z | openssl.base (1.0.2.2100) |
| 3.1 | fips2100b.210323.epkg.Z | openssl.base (20.16.102.2100) |
To extract the fixes from the tar file:
tar xvf openssl_fix33.tar
cd openssl_fix33
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 |
| 6d2cf96d3d8d78af02f92071d50bffeae257dfc136d28ab15957e8e143105045 | 1022100b.210323.epkg.Z |
| 6cfef2f6f82d2dfffd986383bcbfbbaa6041625165ab15028318c956a9afaa53 | fips2100b.210323.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 AIX Support at https://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:
http://aix.software.ibm.com/aix/efixes/security/openssl_advisory33.asc.sig
https://aix.software.ibm.com/aix/efixes/security/openssl_advisory33.asc.sig
ftp://aix.software.ibm.com/aix/efixes/security/openssl_advisory33.asc.s…
B. FIX AND INTERIM FIX INSTALLATION
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
Get Notified about Future Security Bulletins
References
Acknowledgement
Change History
12 Apr 2021: Initial Publication
*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
Was this topic helpful?
Document Information
Modified date:
20 October 2021
UID
ibm16443405