Summary

UPDATED May 17 (Corrected the affected fileset levels for AIX 7.2 TL5 and removed bos.net.tcp.bind 7.2.5.200.): A vulnerability in ISC BIND could allow a remote attacker to cause a denial of service (CVE-2022-38178, CVE-2022-3080, CVE-2022-38177, CVE-2022-2795). AIX uses ISC BIND as part of its DNS functions.

Vulnerability Details

**CVEID:**CVE-2022-38178 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by a memory leak in the DNSSEC verification code for the EdDSA algorithm. By spoofing the target resolver with responses that have a malformed EdDSA signature, a remote attacker could exploit this vulnerability to cause named to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/236706 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-2022-3080 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by an error when stale cache and stale answers are enabled, option stale-answer-client-timeout is set to 0 and there is a stale CNAME in the cache for an incoming query. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause named to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/236704 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-2022-38177 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by a small memory leak in the DNSSEC verification code for the ECDSA algorithm. By spoofing the target resolver with responses that have a malformed ECDSA signature, a remote attacker could exploit this vulnerability to cause named to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/236705 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-2022-2795 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by a flaw in resolver code. By flooding the target resolver with queries, a remote attacker could exploit this vulnerability to severely degrade the resolver’s performance, effectively denying legitimate clients access to the DNS resolution service.
CVSS Base score: 5.3
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/236701 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)

Affected Products and Versions

The following fileset levels are vulnerable:

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.net.tcp.server

Remediation/Fixes

A. APARS

IBM has assigned the following APARs to this problem:

Subscribe to the APARs here:

https://www.ibm.com/support/pages/apar/IJ44422

https://www.ibm.com/support/pages/apar/IJ44423

https://www.ibm.com/support/pages/apar/IJ44424

https://www.ibm.com/support/pages/apar/IJ44425

https://www.ibm.com/support/pages/apar/IJ44426

https://www.ibm.com/support/pages/apar/IJ44427

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 fixes are cumulative and address previously issued AIX/VIOS BIND security bulletins with respect to SP and TL.

The AIX and VIOS fixes can be downloaded via https from:

https://aix.software.ibm.com/aix/efixes/security/bind_fix22.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.

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.

Please reference the Affected Products and Version section above for help with checking installed fileset levels.

For bind.rte on 7.3 TL1 and if installed on 7.2 TL5:

To extract the fixes from the tar file:

tar xvf bind_fix22.tar

cd bind_fix22

Verify you have retrieved the fixes intact:

The checksums below were generated using the “openssl dgst -sha256 [filename]” command as the following:

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/bind_advisory22.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