CVE-2018-5745 in BIND
Summary
by MITRE
"managed-keys" is a feature which allows a BIND resolver to automatically maintain the keys used by trust anchors which operators configure for use in DNSSEC validation. Due to an error in the managed-keys feature it is possible for a BIND server which uses managed-keys to exit due to an assertion failure if, during key rollover, a trust anchor's keys are replaced with keys which use an unsupported algorithm. Versions affected: BIND 9.9.0 -> 9.10.8-P1, 9.11.0 -> 9.11.5-P1, 9.12.0 -> 9.12.3-P1, and versions 9.9.3-S1 -> 9.11.5-S3 of BIND 9 Supported Preview Edition. Versions 9.13.0 -> 9.13.6 of the 9.13 development branch are also affected. Versions prior to BIND 9.9.0 have not been evaluated for vulnerability to CVE-2018-5745.
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Analysis
by VulDB Data Team • 07/20/2024
The vulnerability described in CVE-2018-5745 resides within the managed-keys feature of the Berkeley Internet Name Domain (BIND) resolver implementation, specifically affecting versions ranging from 9.9.0 through 9.10.8-P1, 9.11.0 through 9.11.5-P1, 9.12.0 through 9.12.3-P1, and various supported preview editions. This flaw represents a critical issue in DNS security infrastructure as it directly impacts the ability of DNS resolvers to maintain trust anchors through automated key management processes. The managed-keys functionality is designed to simplify DNSSEC validation by automatically handling key rollovers and trust anchor maintenance, but this automation introduces a potential point of failure when dealing with cryptographic algorithm transitions.
The technical root cause of this vulnerability stems from an assertion failure that occurs during the key rollover process when a trust anchor's keys are replaced with keys utilizing an unsupported algorithm. This assertion failure triggers an abrupt termination of the BIND server process, leading to a denial of service condition that can severely impact DNS resolution capabilities for affected networks. The flaw manifests specifically when the system encounters a scenario where cryptographic algorithms that are not supported by the current BIND implementation are introduced into the trust anchor configuration during automated key management operations. This condition violates the expected operational behavior of the managed-keys subsystem and results in a program termination rather than graceful handling of the unsupported algorithm scenario.
The operational impact of CVE-2018-5745 extends beyond simple service disruption as it fundamentally undermines the reliability of DNSSEC validation mechanisms that organizations depend upon for secure internet communications. When a BIND server implementing managed-keys experiences this assertion failure, it can lead to complete DNS resolution failures for clients relying on that resolver, potentially affecting thousands of users and applications that depend on proper DNS functionality. The vulnerability particularly affects environments where automated key management is enabled and where trust anchor configurations might be updated with newer cryptographic parameters that include algorithm changes. Organizations using DNSSEC validation with managed-keys are at risk of experiencing unannounced service outages that can persist until the affected BIND server is manually restarted or the configuration is corrected.
Security practitioners should recognize this vulnerability as aligning with CWE-248, which addresses "Uncaught Exception," and represents a failure to properly handle exceptional conditions in cryptographic operations. The issue also correlates with ATT&CK technique T1499.001, which describes "Endpoint Denial of Service," as the assertion failure results in service disruption that impacts endpoint availability. Mitigation strategies should focus on immediate patching of affected BIND versions to the latest stable releases that contain the necessary code fixes for proper handling of unsupported algorithm scenarios. Additionally, administrators should consider implementing monitoring solutions to detect potential assertion failures and ensure that trust anchor configurations are carefully reviewed before key rollover operations. Organizations should also consider temporarily disabling managed-keys functionality if immediate patching is not feasible, while implementing manual key management procedures to maintain DNSSEC validation capabilities. The vulnerability demonstrates the critical importance of robust error handling in security-critical infrastructure components, particularly those dealing with cryptographic operations that must maintain system stability even when encountering unexpected configuration parameters.