This vulnerability allows clients using DNS-over-HTTPS (DoH) to exhaust a DNS resolver's CPU and/or memory by flooding it with crafted valid or invalid HTTP/2 traffic. The issue affects multiple versions of BIND 9, specifically versions 9.18.0 through 9.18.32, 9.20.0 through 9.20.4, 9.21.0 through 9.21.3, and 9.18.11-S1 through 9.18.32-S1.
The identified CVSS score for this vulnerability is 7.5, categorizing it as high severity. This means organizations must take prompt action to mitigate potential exploits that could lead to service disruptions. The risk to organizations includes severe availability impacts, as the resource exhaustion could render DNS services unresponsive.
Currently, there are no known exploits available for this vulnerability, but the potential for future exploitation exists. Organizations should prioritize monitoring their systems for any indications of abnormal behavior related to DNS services.
Organizations should prioritize patching immediately. Implementing the latest updates from the vendor will be crucial in safeguarding against this vulnerability.
Vulnerability Details
The vulnerability affects BIND 9 implementations that utilize DNS-over-HTTPS (DoH), which allows clients to query DNS records using HTTPS. Specifically, the issue arises from how these implementations handle crafted HTTP/2 traffic, leading to potential resource exhaustion.
The CVSS vector for this vulnerability is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, indicating that it is network exploitable, has low attack complexity, and requires no privileges or user interaction. Its availability impact is rated as high, which may lead to significant downtime for affected systems.
Published on January 29, 2025, this vulnerability is currently awaiting further analysis. Organizations should stay alert for updates and recommended remediation steps.
Technical Analysis
The root cause of this vulnerability is related to how BIND 9 handles requests over DNS-over-HTTPS. Attackers can exploit this by sending a high volume of requests, which can overwhelm the DNS resolver's resources, leading to potential denial of service.
The attack vector for this vulnerability is through the network, allowing attackers to target DNS resolvers remotely. The attack complexity is low, as no special conditions or configurations are required for an attacker to carry out the attack. The privilege required is none, and user interaction is also not required.
This vulnerability impacts the availability of DNS services severely, with potential disruptions affecting all users relying on the compromised DNS resolver.
Risk & Impact Analysis
The risk to organizations includes significant service disruptions due to the exhaustion of DNS resolver resources. Given the critical role DNS services play in network operations, any downtime can have cascading effects on business continuity and user access.
Organizations that rely heavily on BIND 9 for DNS resolution should assess their exposure and implement necessary mitigations. The urgency for addressing this vulnerability is high, considering its potential implications on availability and service delivery.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerable versions of BIND 9 are as follows: 9.18.0 through 9.18.32, 9.20.0 through 9.20.4, 9.21.0 through 9.21.3, and 9.18.11-S1 through 9.18.32-S1. Organizations using any of these versions should take immediate action to upgrade.
Mitigation & Remediation
To mitigate this vulnerability, organizations should upgrade to the latest patched version of BIND 9. If a patch is not yet available, organizations can limit the rate of DNS queries that their servers handle to reduce the risk of exhaustion. Implementing network controls such as firewalls to filter malicious traffic can also help mitigate the impact.
Penetration testing can also help identify vulnerabilities in the configuration of DNS services that could be exploited.
Detection Guidance
Organizations should monitor DNS logs for unusual patterns, such as spikes in query volume or repeated queries from specific IP addresses. Additionally, monitoring for application performance anomalies and resource usage can provide early indicators of potential exploitation.
AppSecure Threat Intelligence Insight
The long-term significance of this vulnerability lies in the increasing reliance on DNS-over-HTTPS for secure DNS queries. As more organizations adopt this technology, understanding and mitigating associated vulnerabilities becomes critical.
This vulnerability represents a trend of resource exhaustion attacks targeting DNS services, emphasizing the need for robust security measures around DNS infrastructure.
Security teams should prioritize education and awareness of DNS vulnerabilities and their implications for organizational security. Regular assessments and proactive measures are essential to remain resilient against such attacks.
For further insights, organizations may refer to our penetration testing methodology and best practices in vulnerability management.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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