CVE-2014-8500 in BIND
Summary
by MITRE
ISC BIND 9.0.x through 9.8.x, 9.9.0 through 9.9.6, and 9.10.0 through 9.10.1 does not limit delegation chaining, which allows remote attackers to cause a denial of service (memory consumption and named crash) via a large or infinite number of referrals.
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Analysis
by VulDB Data Team • 11/12/2024
The vulnerability identified as CVE-2014-8500 affects the Internet Systems Consortium BIND DNS server software across multiple versions including 9.0.x through 9.8.x, 9.9.0 through 9.9.6, and 9.10.0 through 9.10.1. This issue represents a critical flaw in the DNS resolution process that can be exploited by remote attackers to execute denial of service attacks. The vulnerability specifically stems from the lack of proper limits on delegation chaining within the DNS resolution mechanism, creating a condition where malicious actors can craft specially formatted DNS queries that trigger excessive resource consumption.
The technical flaw manifests when the BIND server processes DNS queries that contain excessive or infinite referral chains without implementing adequate safeguards to prevent such scenarios. When a DNS resolver encounters a referral chain that extends beyond reasonable limits, it begins to consume increasing amounts of memory as it attempts to process each referral in the chain. This memory consumption continues until the system resources are exhausted, leading to the named process crashing and rendering the DNS service unavailable to legitimate users. The vulnerability operates at the core of DNS resolution logic where the server should enforce reasonable limits on the number of delegation hops allowed during recursive queries.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire DNS infrastructure of affected systems. When exploited, attackers can cause sustained denial of service conditions that may require manual intervention to restore normal operations, including restarting the named service or rebooting affected systems. The memory consumption pattern can be particularly devastating in high-traffic environments where the DNS server handles thousands of queries per second, as the resource exhaustion can occur rapidly and without obvious signs of attack. This vulnerability directly impacts the availability aspect of the CIA triad and can be classified under CWE-400 as an uncontrolled resource consumption issue.
From an attack perspective, this vulnerability aligns with several techniques documented in the MITRE ATT&CK framework, particularly those related to denial of service attacks and resource exhaustion. The attack vector involves sending malformed DNS queries that exploit the lack of delegation chain limits, making it a straightforward exploitation method that requires minimal technical sophistication. The vulnerability also relates to technique T1499 which covers network denial of service attacks and T1583 which involves resource hijacking through malicious code or configuration flaws. Organizations running affected BIND versions face significant risk as this vulnerability can be exploited by automated scanning tools to identify and compromise vulnerable systems.
The recommended mitigations for CVE-2014-8500 include immediate patching of affected BIND versions to the latest stable releases that contain the necessary fixes for delegation chain limiting. Administrators should implement proper configuration parameters such as setting appropriate limits on the number of referral hops allowed during recursive queries, typically through the use of the max-ncache-ttl and max-cache-ttl directives in the named.conf file. Network-level protections including rate limiting and access control lists can provide additional layers of defense against exploitation attempts. Organizations should also implement monitoring systems to detect unusual DNS query patterns that may indicate exploitation attempts, as the memory consumption behavior can be monitored through system resource utilization metrics. The fix for this vulnerability represents a fundamental security enhancement that addresses the core architectural flaw in how delegation chains are handled within the DNS resolution process.