CVE-2019-13416 in Search Guard
Summary
by MITRE
Search Guard versions before 24.3 had an issue when Cross Cluster Search (CCS) was enabled, authenticated users are always authorized on the local cluster ignoring their roles on the remote cluster(s).
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Analysis
by VulDB Data Team • 07/27/2020
The vulnerability identified as CVE-2019-13416 affects Search Guard implementations prior to version 24.3 and specifically impacts Cross Cluster Search functionality within Elasticsearch environments. This security flaw represents a critical authorization bypass issue that undermines the fundamental security model of distributed search operations. When Cross Cluster Search is enabled, the system should maintain proper role-based access controls across all connected clusters, ensuring that user permissions are consistently enforced regardless of which cluster they are accessing. However, this vulnerability causes the system to ignore remote cluster role definitions and instead authorize all authenticated users solely based on their local cluster permissions, creating a significant security gap that could allow unauthorized access to remote cluster data.
The technical flaw stems from improper implementation of cross-cluster authorization logic within the Search Guard plugin architecture. The system fails to properly validate and enforce role-based access controls when users attempt to access remote clusters through Cross Cluster Search operations. This misconfiguration allows authenticated users to bypass the intended security boundaries that should separate access permissions between different clusters. The vulnerability specifically affects the authorization mechanism that should validate user roles against remote cluster configurations, instead defaulting to local cluster permissions regardless of the actual security requirements. This behavior creates a scenario where users who may have restricted access on remote clusters can gain elevated privileges through local cluster authentication, effectively breaking the principle of least privilege that should govern distributed search environments.
The operational impact of this vulnerability is substantial as it enables unauthorized data access across cluster boundaries, potentially exposing sensitive information stored in remote Elasticsearch clusters. Attackers who can authenticate to a local cluster can exploit this flaw to access data from connected remote clusters without proper authorization, effectively circumventing the security controls designed to protect cross-cluster data access. This vulnerability particularly affects organizations that rely on distributed Elasticsearch architectures where multiple clusters serve different security domains or business units. The implications extend beyond simple data access violations as the flaw could enable attackers to perform reconnaissance across multiple clusters, potentially identifying additional targets or gathering intelligence about the broader distributed environment. The vulnerability also impacts audit and compliance requirements since access logs may not accurately reflect true access patterns due to the bypassed authorization checks.
Organizations should immediately upgrade to Search Guard version 24.3 or later to address this vulnerability, as the fix implements proper cross-cluster role validation and authorization enforcement. Administrators should also conduct thorough access control reviews to identify any existing unauthorized access patterns that may have occurred due to this vulnerability. The mitigation strategy should include implementing additional monitoring controls to detect anomalous access patterns across cluster boundaries and ensuring that proper role definitions are maintained for all clusters within the distributed environment. This vulnerability aligns with CWE-284 (Improper Access Control) and represents a specific implementation weakness in distributed authorization systems. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques and can be leveraged to move laterally across cluster boundaries, potentially enabling more extensive attacks within the Elasticsearch infrastructure. The fix implemented in version 24.3 addresses the core authorization logic to ensure that user roles are properly validated against remote cluster configurations, restoring the intended security boundaries that protect distributed search environments.