CVE-2017-3140 in BIND
Summary
by MITRE
If named is configured to use Response Policy Zones (RPZ) an error processing some rule types can lead to a condition where BIND will endlessly loop while handling a query. Affects BIND 9.9.10, 9.10.5, 9.11.0->9.11.1, 9.9.10-S1, 9.10.5-S1.
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Analysis
by VulDB Data Team • 07/01/2023
The vulnerability identified as CVE-2017-3140 represents a critical denial of service flaw within the Berkeley Internet Name Domain (BIND) software suite, specifically affecting versions ranging from 9.9.10 through 9.11.1 and their corresponding service pack releases. This issue manifests when BIND is configured with Response Policy Zones functionality, a feature designed to provide policy-based responses to DNS queries based on predefined rules. The flaw occurs during the processing of certain rule types within the RPZ configuration, creating a scenario where the DNS resolver enters an infinite loop while attempting to handle incoming queries. This behavior fundamentally undermines the availability of the DNS service, as legitimate queries become unresponsive and the server consumes excessive computational resources.
The technical root cause of this vulnerability stems from improper error handling within BIND's RPZ processing module, where specific combinations of rule types trigger an iterative processing condition that lacks proper termination criteria. When the resolver encounters certain malformed or complex RPZ rules, the internal state management fails to properly break out of the processing loop, causing the system to continuously re-evaluate the same query without making progress. This condition is particularly dangerous because it can be triggered by malformed DNS queries or crafted payloads that exploit the specific rule processing path, making it potentially exploitable by remote attackers. The vulnerability aligns with CWE-835, which addresses infinite loops in software implementations, and demonstrates how seemingly minor error handling deficiencies can lead to catastrophic availability failures in critical network infrastructure components.
The operational impact of CVE-2017-3140 extends beyond simple service disruption, as it can effectively render DNS servers completely unresponsive to legitimate traffic while consuming significant system resources. This makes the vulnerability particularly dangerous in production environments where DNS availability is critical for network operations, web browsing, email services, and other internet-dependent applications. The infinite loop condition can cause memory exhaustion, CPU saturation, and overall system instability, potentially affecting multiple services that depend on the compromised DNS infrastructure. Attackers could leverage this vulnerability to perform denial of service attacks against DNS servers, causing cascading failures throughout affected networks. The vulnerability also aligns with ATT&CK technique T1499.004, which describes network denial of service attacks targeting DNS services, making it a significant concern for organizations maintaining DNS infrastructure as part of their cybersecurity posture.
Mitigation strategies for CVE-2017-3140 primarily involve immediate patching of affected BIND versions to the latest stable releases that contain the necessary fixes for the RPZ processing error handling. Organizations should also implement monitoring systems to detect unusual resource consumption patterns that might indicate exploitation attempts, as well as configure rate limiting and query filtering mechanisms to reduce the impact of potential attacks. Network administrators should review their RPZ configurations to identify and remove or simplify problematic rule sets that might trigger the vulnerable code paths. Additionally, implementing redundant DNS infrastructure and proper incident response procedures can help minimize the operational impact should exploitation occur, while regular vulnerability assessments and security audits should be conducted to identify similar issues in other network infrastructure components. The fix implemented in subsequent versions addresses the core loop termination issue by adding proper bounds checking and error recovery mechanisms within the RPZ rule processing logic.