CVE-2020-5864 in Controller
Summary
by MITRE
In versions of NGINX Controller prior to 3.2.0, communication between NGINX Controller and NGINX Plus instances skip TLS verification by default.
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Analysis
by VulDB Data Team • 06/02/2024
The vulnerability identified as CVE-2020-5864 affects NGINX Controller versions prior to 3.2.0 and represents a critical security flaw in the communication protocol between the controller and NGINX Plus instances. This issue stems from the default configuration that bypasses TLS certificate verification during inter-component communication, creating a significant attack surface that adversaries can exploit to compromise the entire system. The vulnerability specifically targets the secure communication channels that should establish trust between management components and the managed NGINX Plus instances, fundamentally undermining the security posture of organizations relying on this infrastructure.
The technical flaw manifests as a misconfiguration in the TLS implementation where the NGINX Controller fails to validate the authenticity of certificates presented by NGINX Plus instances during the connection establishment process. This default behavior allows man-in-the-middle attacks to occur seamlessly, as the system accepts any certificate without proper validation, including self-signed certificates or certificates from untrusted authorities. The vulnerability directly maps to CWE-295 which specifically addresses improper certificate validation and certificate chain verification issues in security protocols. When TLS verification is disabled, attackers can intercept, modify, or redirect communication between the controller and the plus instances, potentially gaining unauthorized access to sensitive configuration data, operational metrics, and control commands.
The operational impact of this vulnerability extends beyond simple data interception, as it enables attackers to manipulate the configuration of NGINX Plus instances through the compromised controller communication channel. This creates a persistent threat vector that can lead to service disruption, data exfiltration, and potential lateral movement within the network infrastructure. Organizations using affected versions face significant risk of unauthorized modifications to load balancing configurations, SSL termination settings, and other critical operational parameters that govern their web traffic handling. The attack surface is particularly concerning in environments where NGINX Controller manages multiple NGINX Plus instances across different network segments, as a successful exploitation can provide attackers with comprehensive control over the entire web infrastructure management layer.
Security mitigation strategies for CVE-2020-5864 require immediate implementation of the vendor-released patch version 3.2.0 or later, which properly enforces TLS certificate verification. Organizations should also conduct comprehensive audits of their existing NGINX Controller deployments to identify any instances running vulnerable versions and ensure that all communication channels between controller and plus instances enforce strict certificate validation. Network segmentation and monitoring should be enhanced to detect anomalous communication patterns that might indicate exploitation attempts. The remediation process should include configuration reviews to ensure that certificate authorities are properly configured and that certificate revocation checking is enabled. This vulnerability aligns with ATT&CK technique T1046 which involves network service scanning and T1566 which covers credential harvesting through network attacks, making it a critical target for immediate remediation to prevent broader compromise of the organization's web infrastructure and operational security posture.