CVE-2022-3924 : Exploit Details and Defense Strategies

A vulnerability has been identified in BIND 9, where the 'named' service configured to answer from stale cache may terminate unexpectedly at recursive-clients soft quota.

Understanding CVE-2022-3924

This vulnerability, affecting BIND 9 versions, poses a threat of potential denial of service due to an assertion failure under specific conditions.

What is CVE-2022-3924?

The issue arises in BIND 9 resolvers utilizing certain configurations, leading to a race condition that can trigger a crash in the 'named' service.

The Impact of CVE-2022-3924

An attacker can exploit the vulnerability by sending specific queries to the resolver, causing the 'named' service to crash.

Technical Details of CVE-2022-3924

The vulnerability affects various versions of BIND 9 and is characterized by a CVSS base score of 7.5 (High severity) due to its potential impact on service availability.

Vulnerability Description

The issue occurs when stale-answer-client-timeout is configured with a value greater than zero, resulting in a race between responding to client queries and timeout SERVFAIL conditions.

Affected Systems and Versions

BIND 9 versions impacted include 9.16.12 to 9.16.36, 9.18.0 to 9.18.10, 9.19.0 to 9.19.8, and 9.16.12-S1 to 9.16.36-S1.

Exploitation Mechanism

Exploitation involves sending specific queries to the resolver, triggering a crash in the 'named' service.

Mitigation and Prevention

Take immediate steps to address the vulnerability and prevent potential exploitation.

Immediate Steps to Take

Disabling 'stale-answer-client-timeout' or setting the timeout value to zero can mitigate the issue. However, it is crucial to maintain the 'recursive-clients' limit.

Long-Term Security Practices

Upgrade to the patched releases provided by ISC to mitigate the vulnerability effectively.

Patching and Updates

To address CVE-2022-3924, upgrade to one of the patched releases closely related to your current BIND 9 version: 9.16.37, 9.18.11, 9.19.9, or 9.16.37-S1.