Security Bulletin
Summary
A vulnerability in zlib and zlibNX could allow a remote attacker to cause a denial of service (CVE-2018-25032). AIX uses zlib and zlibNX as part of its data compression functions.
Vulnerability Details
CVEID: CVE-2018-25032
DESCRIPTION: Zlib is vulnerable to a denial of service, caused by a memory corruption in the deflate operation. By using many distant matches, a remote 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/222615 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)
DESCRIPTION: Zlib is vulnerable to a denial of service, caused by a memory corruption in the deflate operation. By using many distant matches, a remote 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/222615 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 |
| AIX | 7.3 |
| VIOS | 3.1 |
The following fileset levels are vulnerable:
For zlib:
| Fileset | Lower Level | Upper Level |
| rpm.rte | 4.9.1.3 | 4.15.1.1005 |
| rpm.rte | 4.15.1.2000 | 4.15.1.2005 |
For zlibNX:
| Fileset | Lower Level | Upper Level |
| zlibNX.rte | 7.2.4.0 | 7.2.4.7 |
| zlibNX.rte | 7.3.0.0 | 7.3.0.1 |
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 zlibNX.rte
Remediation/Fixes
A. FIXES
IBM strongly recommends addressing the vulnerability now.
AIX and VIOS fixes are available.
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.
For zlib:
| AIX Level | Fix |
| 7.1, 7.2 | rpm.rte.4.15.1.1006 |
| 7.3 | rpm.rte.4.15.1.2006 |
| VIOS Level | Fix |
| 3.1 | rpm.rte.4.15.1.1006 |
For zlibNX:
| AIX Level | Fix |
| 7.2 | IJ41754s4a.220829.epkg.Z |
| 7.3 | IJ42198s2a.220829.epkg.Z |
| VIOS Level | Fix |
| 3.1 | IJ41754s4a.220829.epkg.Z |
To extract the fixes from the tar file:
tar xvf zlib_fix.tar
cd zlib_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 |
| 6e830be2ce0057d12072bef887337b39a5fb97cc6fceafbdf3c9d1c8f6bda8be | IJ41754s4a.220829.epkg.Z |
| 91b35e4f334463f49d76e263c70fa8dce09dbc9825d3bb7640b8d186511dfd02 | IJ42198s2a.220829.epkg.Z |
| f12ab2fa1cce9129dc27f2d8a6af1f3e5a1075c93da87ff5f67519d19cfd8db1 | rpm.rte.4.15.1.1006 |
| 942c99ecb388645676e3f9361b0157406997188f4249ff7d07ee58bf3271cc34 | rpm.rte.4.15.1.2006 |
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:
B. 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:
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
28 Sep 2022: 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
[{"Type":"MASTER","Line of Business":{"code":"LOB57","label":"Power"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSPHKW","label":"PowerVM Virtual I\/O Server"},"ARM Category":[],"Platform":[{"code":"PF002","label":"AIX"}],"Version":"All Versions"},{"Type":"MASTER","Line of Business":{"code":"LOB08","label":"Cognitive Systems"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SWG10","label":"AIX"},"ARM Category":[{"code":"a8m0z000000cvzhAAA","label":"Security"}],"Platform":[{"code":"PF002","label":"AIX"}],"Version":"7.1.0;7.2.0;7.3.0"}]
Was this topic helpful?
Document Information
Modified date:
28 September 2022
Initial Publish date:
28 September 2022
UID
ibm16824891