CVE-2018-1110 in knot-resolver
Summary
by MITRE • 03/30/2021
A flaw was found in knot-resolver before version 2.3.0. Malformed DNS messages may cause denial of service.
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Analysis
by VulDB Data Team • 08/14/2024
The vulnerability identified as CVE-2018-1110 represents a critical denial of service flaw affecting knot-resolver versions prior to 230. This DNS resolver implementation demonstrates a fundamental weakness in input validation and error handling mechanisms that can be exploited to disrupt network services. The issue stems from the resolver's inability to properly process malformed DNS messages, creating a pathway for malicious actors to intentionally crash or render the resolver service unavailable. Such vulnerabilities are particularly dangerous in network infrastructure components where DNS resolution is critical for system operations and user connectivity. The flaw directly impacts the reliability and availability of services that depend on knot-resolver for DNS resolution, potentially affecting large-scale deployments where this resolver is used as a core component in network infrastructure.
The technical root cause of this vulnerability lies in insufficient validation of DNS message structures within the knot-resolver implementation. When processing malformed DNS packets, the resolver fails to properly handle unexpected or invalid message formats, leading to abrupt termination of the resolver process or system instability. This represents a classic buffer overflow or memory corruption scenario where malformed input data causes the application to behave unpredictably. The vulnerability aligns with CWE-122, which addresses heap-based buffer overflow conditions, and CWE-248, which covers exposure of exception information. From an operational perspective, this flaw creates an attack surface where adversaries can craft specifically malformed DNS responses or queries to trigger the resolver's crash behavior, effectively creating a denial of service condition that can persist until manual intervention or service restart occurs.
The operational impact of CVE-2018-1110 extends beyond simple service disruption to potentially affect broader network operations and availability. Organizations relying on knot-resolver for DNS resolution may experience cascading failures where dependent services become unreachable due to the resolver's inability to process DNS queries. This vulnerability particularly affects environments where DNS resolution is critical for application functionality, network security controls, or infrastructure management systems. The attack vector requires minimal technical expertise to exploit, as it only requires sending malformed DNS messages to the vulnerable resolver instance. From an adversarial perspective, this flaw aligns with ATT&CK technique T1499.004, which covers network disruption through service availability attacks. The vulnerability also intersects with ATT&CK technique T1071.004, which involves application layer protocol manipulation, as DNS protocol manipulation can be used to exploit this specific weakness.
Mitigation strategies for CVE-2018-1110 primarily focus on upgrading to knot-resolver version 2.3.0 or later, which includes proper input validation and error handling mechanisms. Organizations should implement comprehensive patch management procedures to ensure all instances of knot-resolver are updated promptly. Additional defensive measures include implementing network-level filtering to detect and block malformed DNS traffic patterns, deploying monitoring solutions to identify unusual resolver behavior, and establishing automated alerting systems for service availability issues. The vulnerability also underscores the importance of input validation and robust error handling in network infrastructure components, as highlighted by industry best practices in secure coding standards. Organizations should conduct vulnerability assessments to identify all instances of affected knot-resolver versions and prioritize remediation efforts based on risk assessment of their specific deployments. Network segmentation and access control measures can provide additional defense-in-depth layers to limit the impact of potential exploitation attempts.