Security Bulletin: IBM i DNS is affected by denial of service attacks due to flaws in ISC BIND (CVE-2022-3094, CVE-2022-3736, CVE-2022-3924).

Summary

The IBM i DNS Server implementation uses ISC BIND. ISC BIND is vulnerable to denial of service attacks due to allocating memory before checking access permissions and flaws in the implementation of the stale-answer-client-timeout option as described in the vulnerability details section. IBM i has addressed the applicable CVEs with a fix to IBM i DNS as described in the remediation/fixes section.

Vulnerability Details

CVEID:CVE-2022-3094
**DESCRIPTION:**ISC BIND is vulnerable to a denial of service, caused by the allocation of memory prior to the checking of access permissions (ACLs). By sending an UPDATE message flood, a remote attacker could exploit this vulnerability to cause named to exhaust all available memory.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/245430 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-2022-3924
**DESCRIPTION:**ISC BIND is vulnerable to a denial of service, caused by a flaw in the implementation of the stale-answer-client-timeout option. By sending specific queries to the resolver, 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/245432 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-2022-3736
**DESCRIPTION:**ISC BIND is vulnerable to a denial of service, caused by a flaw in the implementation of the stale-answer-client-timeout option. By sending RRSIG queries to the resolver, a remote attacker could exploit this vulnerability to cause named to crash when stale cache and stale answers are enabled.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/245431 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

Remediation/Fixes

The issue can be fixed by applying a PTF to IBM i. Releases 7.5, 7.4, 7.3, and 7.2 of IBM i will be fixed.

The IBM i PTF numbers for 5770-SS1 Option 31 Domain Name System contain the fix for the vulnerabilities.

IBM i Release| 5770-SS1
Option 31
PTF Number| PTF Download Link
—|—|—
7.5| SI82623| <https://www.ibm.com/support/pages/ptf/SI82623&gt;
7.4| SI82624| <https://www.ibm.com/support/pages/ptf/SI82624&gt;
7.3| SI82625| <https://www.ibm.com/support/pages/ptf/SI82625&gt;
7.2| SI82626| <https://www.ibm.com/support/pages/ptf/SI82626&gt;

<https://www.ibm.com/support/fixcentral/&gt;

_Important note: __IBM recommends that all users running unsupported versions of affected products upgrade to supported and fixed version of affected products.
_

Workarounds and Mitigations

None