Critical Bind Dns Software Flaws Enable Remote Dos Attacks

By Editor Last updated Mrz 4, 2025

This article examines the critical vulnerabilities found in BIND DNS software, which have the potential to enable remote denial-of-service (DoS) attacks. The vulnerabilities, identified as CVE-2022-3094, CVE-2022-3736, and CVE-2022-3924, pose significant risks to the security and stability of BIND DNS systems. The first vulnerability allows for a memory allocation crash through dynamic DNS updates, affecting BIND 9.11 and earlier versions. This flaw can result in server memory exhaustion if unaccepted dynamic updates flood the system from trusted clients. The second vulnerability causes the resolver to crash when receiving a specific RRSIG query with enabled stale cache and stale responses. The third vulnerability is associated with the implementation of the stale-answer-client-timeout, leading to named crashing due to a race condition between outdated responses and timeout SERVFAIL. To mitigate these vulnerabilities, it is strongly recommended to update BIND DNS software to versions 9.16.37, 9.18.11, or 9.19.9. It is crucial to address these flaws promptly to prevent potential exploitation by malicious actors.

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Key Takeaways

BIND DNS software has three high-severity vulnerabilities (CVE-2022-3094, CVE-2022-3736, and CVE-2022-3924) that can be exploited by hackers to trigger remote Denial of Service (DoS) attacks.
The first vulnerability allows a memory allocation crash through dynamic DNS updates and affects BIND 9.11 and previous versions.
The second vulnerability causes the resolver to crash when receiving RRSIG queries with specific settings, but requires stale cache and stale responses to be enabled.
The third vulnerability is related to the implementation of the stale-answer-client-timeout and can result in named crashing. It is caused by a race condition between an outdated response and a timeout SERVFAIL.
To mitigate these vulnerabilities, it is recommended to update BIND DNS software to versions 9.16.37, 9.18.11, or 9.19.9. Immediate update is advised, even though there are no known exploit cases. Additionally, the BIND preview edition version 9.16.37-S1 fixes a separate flaw (CVE-2022-3488).

Critical Vulnerabilities

The pre-existing knowledge highlights the presence of critical vulnerabilities in BIND DNS software, including CVE-2022-3094, CVE-2022-3736, and CVE-2022-3924, which can be exploited to trigger remote DoS attacks. These vulnerabilities pose potential exploits that can have a significant impact on the security and functionality of the BIND DNS software. The first vulnerability, CVE-2022-3094, allows for a memory allocation crash through dynamic DNS updates. While the scope of this vulnerability is limited to trusted clients making dynamic zone changes, a flood of unaccepted dynamic updates can exhaust server memory. The second vulnerability, CVE-2022-3736, results in resolver crashes when receiving RRSIG queries with specific settings, provided that stale cache and stale responses are enabled. Lastly, CVE-2022-3924 presents an issue with the implementation of the stale-answer-client-timeout, leading to a race condition between outdated responses and timeout SERVFAIL, potentially causing named to crash. An impact assessment of these vulnerabilities emphasizes the urgent need for immediate updates to the BIND DNS software to mitigate the risk of remote DoS attacks.

Affected Versions and Impact

Affected versions of the BIND DNS software have been identified, and these versions are susceptible to high-severity vulnerabilities that can result in denial-of-service attacks. To protect BIND DNS servers from remote DoS attacks, mitigation strategies should be implemented. One important aspect is vulnerability management, which plays a crucial role in maintaining a secure DNS infrastructure. Regularly updating the BIND DNS software to the latest versions, such as BIND versions 9.16.37, 9.18.11, and 9.19.9, is essential to fix the identified vulnerabilities. By promptly applying these updates, potential exploits can be mitigated, reducing the risk of DoS attacks. Additionally, organizations should stay informed about the latest cybersecurity news and follow best practices outlined in the network security checklist to enhance their DNS server’s security posture.

Recommended Updates

To ensure the security of DNS servers, it is advisable to promptly apply the recommended updates to address the identified vulnerabilities in the BIND software. Immediate updates are of utmost importance due to the potential impact of Denial-of-Service (DoS) attacks. These critical flaws in the BIND DNS software can be exploited by hackers to remotely trigger DoS attacks, leading to service disruption and potentially compromising the availability of DNS services. The vulnerabilities include memory allocation crashes through dynamic DNS updates, resolver crashes when receiving RRSIG queries with specific settings, and issues with the stale-answer-client-timeout implementation. While there have been no known exploitations of these vulnerabilities, it is crucial to update to BIND versions 9.16.37, 9.18.11, and 9.19.9 to mitigate the risk of potential DoS attacks and ensure the stability and reliability of DNS servers.

Frequently Asked Questions

Can the BIND DNS software vulnerabilities be exploited remotely?

Yes, the vulnerabilities in BIND DNS software can be exploited remotely to trigger DoS attacks. These flaws allow attackers to crash the software by sending specific queries or flood the server with unaccepted dynamic updates, causing a depletion of server memory.

Are there any known instances of these vulnerabilities being exploited?

There are no known instances of the BIND DNS vulnerabilities being exploited. However, these vulnerabilities have the potential to impact network security by allowing remote denial-of-service attacks and crashing the BIND DNS software.

How can the BIND DNS software vulnerabilities be mitigated?

To mitigate BIND DNS software vulnerabilities and enhance BIND DNS security, it is recommended to update the software to the latest versions (9.16.37, 9.18.11, and 9.19.9) that fix the identified flaws. Immediate updating is advised to prevent potential exploitation.

Are there any alternative DNS software options that can be used instead of BIND?

Alternative DNS software options include PowerDNS, Knot DNS, and NSD. Pros include better performance, security, and flexibility. Cons include a learning curve and potential compatibility issues. Organizations should evaluate their specific needs before choosing an alternative DNS software.

Are there any additional steps or best practices that can be implemented to enhance the security of DNS servers?

To enhance the security of DNS servers, several techniques can be implemented. These include regularly updating DNS software, implementing DNSSEC for data integrity, using firewalls and access controls, monitoring DNS traffic, and implementing DNS server redundancy. These measures can help protect against potential vulnerabilities and mitigate the risk of attacks.