CVE-2023-5680 in BIND
Summary
by MITRE • 02/13/2024
If a resolver cache has a very large number of ECS records stored for the same name, the process of cleaning the cache database node for this name can significantly impair query performance. This issue affects BIND 9 versions 9.11.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.45-S1, and 9.18.11-S1 through 9.18.21-S1.
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Analysis
by VulDB Data Team • 03/04/2024
The vulnerability described in CVE-2023-5680 represents a significant performance degradation issue within the Berkeley Internet Name Domain software commonly known as BIND. This flaw specifically targets the resolver cache mechanism and manifests when an excessive number of EDNS Client Subnet (ECS) records are stored for a single domain name. The issue stems from inefficient cache cleanup operations that become increasingly burdensome as the number of ECS records grows, leading to substantial query performance degradation. The affected versions span multiple release branches of BIND 9, including the long-term support versions 9.11.x, 9.16.x, and 9.18.x, indicating this is a persistent issue across the software lineage that requires careful attention from system administrators and security professionals.
The technical root cause of this vulnerability lies in how BIND handles cache cleanup operations when processing large numbers of ECS records for identical domain names. When the cache maintenance process attempts to remove or update database nodes containing these records, the computational overhead becomes disproportionately high. This performance degradation occurs because the cleanup algorithm does not scale efficiently with the number of records, resulting in extended processing times for each cache operation. The issue is particularly concerning because ECS records are commonly used for traffic management and geographic routing, making their accumulation in the cache database a realistic scenario in production environments. This behavior directly relates to CWE-798, which addresses the use of hardcoded credentials and improper resource management, as the system's resource utilization becomes inefficient and potentially exploitable under certain conditions.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially affect the availability and responsiveness of DNS services. When cache cleanup operations become time-consuming, the DNS resolver may experience significant delays in processing queries, leading to increased latency for end users and potential service disruption. This issue can be particularly problematic in high-traffic environments where ECS records are frequently updated or when malicious actors deliberately attempt to trigger cache pollution attacks. The vulnerability creates a scenario where legitimate DNS operations become increasingly slow, potentially allowing for denial of service conditions. From an attacker perspective, this weakness aligns with ATT&CK technique T1499.004, which involves network disruption through resource exhaustion, as the cache pollution can effectively consume system resources and degrade performance without requiring sophisticated exploitation techniques.
Mitigation strategies for CVE-2023-5680 should focus on both immediate operational adjustments and long-term architectural improvements. System administrators should monitor cache utilization patterns and implement appropriate limits on ECS record storage to prevent excessive accumulation. The recommended approach involves upgrading to patched versions of BIND 9 where the cache cleanup algorithms have been optimized to handle large numbers of ECS records more efficiently. Additionally, implementing proper cache management policies that include regular monitoring of cache sizes and automated cleanup procedures can help prevent the accumulation of problematic record sets. Organizations should also consider implementing rate limiting mechanisms for ECS record updates and establishing baseline performance metrics to quickly identify when cache operations begin to degrade. The vulnerability underscores the importance of proper resource management and efficient algorithm design in DNS infrastructure, particularly for systems that handle high volumes of client subnet information.