CVE-2022-32983 in Knot Resolver
Summary
by MITRE • 06/20/2022
Knot Resolver through 5.5.1 may allow DNS cache poisoning when there is an attempt to limit forwarding actions by filters.
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Analysis
by VulDB Data Team • 06/20/2022
CVE-2022-32983 represents a significant vulnerability in Knot Resolver version 5.5.1 and earlier, which exposes the DNS caching system to potential cache poisoning attacks through flawed forwarding filter implementations. This vulnerability specifically targets the resolver's mechanism for limiting forwarding actions, creating a pathway for malicious actors to manipulate DNS responses and potentially redirect traffic to fraudulent destinations. The flaw arises from insufficient validation of forwarded DNS queries when filters are applied to restrict forwarding behavior, allowing attackers to exploit the system's trust in legitimate forwarding processes.
The technical implementation of this vulnerability stems from the resolver's handling of DNS forwarding operations where filter mechanisms are designed to control which queries are forwarded to upstream servers. When these filters fail to properly validate or sanitize forwarded queries, an attacker can craft malicious responses that appear to originate from legitimate upstream servers. This occurs because the resolver's cache does not adequately verify the authenticity of responses received through filtered forwarding paths, creating opportunities for attackers to inject false DNS records into the cache. The vulnerability operates at the intersection of DNS security protocols and access control mechanisms, where the expectation of filtered forwarding security is undermined by inadequate validation checks.
From an operational impact perspective, this vulnerability poses serious risks to DNS infrastructure integrity and can lead to widespread service disruption and potential data exfiltration. Organizations relying on Knot Resolver for DNS caching may experience unauthorized redirection of traffic, compromised domain resolution, and potential exposure of sensitive network information. The attack surface extends beyond individual resolver instances to affect entire DNS ecosystems where the resolver serves as a caching server for multiple clients. This vulnerability particularly impacts environments where DNS security is paramount, such as enterprise networks, cloud deployments, and critical infrastructure systems where maintaining DNS integrity is essential for overall network security.
The vulnerability aligns with CWE-284 Access Control and CWE-347 Improper Verification of Cryptographic Signature categories, representing a failure in proper access control validation and response verification mechanisms. It also maps to ATT&CK technique T1071.004 Application Layer Protocol DNS, as it exploits DNS protocol weaknesses to achieve malicious objectives. Organizations should implement immediate mitigations including updating to Knot Resolver version 5.5.2 or later, which contains patches addressing the forwarding filter validation issues. Additionally, administrators should review and strengthen DNS security configurations, implement additional monitoring for suspicious DNS forwarding patterns, and consider deploying DNS security extensions such as DNSSEC to provide additional layers of protection against cache poisoning attacks. The fix typically involves enhanced validation of forwarded DNS responses and stricter enforcement of forwarding filter rules to prevent malicious injection of cache entries.