CVE-2021-25215 in Tekelec Platform Distribution
Summary
by MITRE • 04/29/2021
In BIND 9.0.0 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.9.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.11 of the BIND 9.17 development branch, when a vulnerable version of named receives a query for a record triggering the flaw described above, the named process will terminate due to a failed assertion check. The vulnerability affects all currently maintained BIND 9 branches (9.11, 9.11-S, 9.16, 9.16-S, 9.17) as well as all other versions of BIND 9.
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Analysis
by VulDB Data Team • 10/24/2021
The vulnerability identified as CVE-2021-25215 represents a critical assertion failure in the Berkeley Internet Name Domain (BIND) software that affects multiple versions across different release branches. This flaw exists within the core DNS server functionality where the named process experiences a crash when processing specific query requests that trigger an assertion check failure. The vulnerability impacts all currently maintained BIND 9 branches including 9.11, 9.11-S, 9.16, 9.16-S, and 9.17, making it particularly widespread across the DNS server ecosystem. The affected versions span from 9.0.0 through 9.11.29, 9.12.0 through 9.16.13, and the supported preview editions with similar version ranges, indicating this is not an isolated incident but rather a systemic issue within the DNS server implementation.
The technical nature of this vulnerability stems from a failed assertion check that occurs when the named process receives a specially crafted DNS query that triggers a specific record processing scenario. An assertion failure typically occurs when the software encounters a condition that violates expected program behavior, causing the process to terminate abruptly. This particular flaw manifests when the DNS server processes a query for a record that activates the problematic code path, leading to an assertion that fails and subsequently terminates the named process. The vulnerability is classified as a denial of service condition that can be exploited by remote attackers who send malicious DNS queries to the affected server, causing legitimate DNS service to become unavailable. This behavior aligns with CWE-617, which describes reachable assertion conditions that can lead to program termination and denial of service scenarios.
The operational impact of CVE-2021-25215 extends beyond simple service disruption as it can effectively disable DNS resolution capabilities on affected systems, potentially affecting thousands of network services that depend on proper DNS functionality. When the named process terminates due to the assertion failure, all DNS queries processed by that server will fail until the service is manually restarted, creating cascading failures across network infrastructure that relies on the affected DNS server. This vulnerability is particularly concerning because DNS servers are fundamental infrastructure components that many organizations depend upon for internal and external network communications. The attack surface is broad since any system running an affected version of BIND is potentially vulnerable to remote exploitation, making this a critical security concern for network administrators and security teams responsible for maintaining DNS infrastructure.
Mitigation strategies for this vulnerability should prioritize immediate patching of all affected BIND versions to the latest stable releases that contain the necessary code fixes. Organizations should implement monitoring solutions to detect unusual termination patterns or service disruptions that might indicate exploitation attempts. Network segmentation and access controls should be reviewed to limit exposure of DNS servers to untrusted networks, while implementing rate limiting and query filtering mechanisms to reduce the potential impact of malicious queries. The vulnerability's classification under ATT&CK technique T1496 suggests that defensive measures should include process monitoring and anomaly detection to identify unauthorized termination of critical DNS services. Additionally, administrators should consider implementing redundant DNS infrastructure and failover mechanisms to ensure continued service availability even if individual servers are compromised by this vulnerability. Regular security assessments and vulnerability scanning should be conducted to identify any other potentially affected systems within the network infrastructure.