CVE-2024-23451 in Elasticsearch
Summary
by MITRE • 03/27/2024
Incorrect Authorization issue exists in the API key based security model for Remote Cluster Security, which is currently in Beta, in Elasticsearch 8.10.0 and before 8.13.0. This allows a malicious user with a valid API key for a remote cluster configured to use the new Remote Cluster Security to read arbitrary documents from any index on the remote cluster, and only if they use the Elasticsearch custom transport protocol to issue requests with the target index ID, the shard ID and the document ID. None of Elasticsearch REST API endpoints are affected by this issue.
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Analysis
by VulDB Data Team • 03/27/2024
The vulnerability described in CVE-2024-23451 represents a critical authorization flaw within Elasticsearch's Remote Cluster Security feature, which was introduced in a beta state and remained unpatched until version 8.13.0. This issue specifically targets the API key based security model that governs remote cluster communications, creating a significant security gap that could be exploited by malicious actors. The vulnerability exists in Elasticsearch versions 8.10.0 through 8.12.9, making it a widespread concern for organizations that have not yet upgraded their systems. The flaw manifests in the authorization mechanisms that should prevent unauthorized access to remote cluster data, yet fails to properly validate access permissions for specific types of requests.
The technical implementation of this vulnerability stems from an insufficient authorization check within the custom transport protocol layer of Elasticsearch. When a malicious user possesses a valid API key for a remote cluster configured with the new Remote Cluster Security model, they can bypass normal access controls to read documents from any index on the remote cluster. This occurs specifically when requests are made using the Elasticsearch custom transport protocol with explicit parameters including the target index ID, shard ID, and document ID. The vulnerability does not affect the standard REST API endpoints, which suggests that the authorization failure is isolated to the transport protocol implementation rather than being a broader architectural issue. This targeted nature of the flaw indicates that the security controls are properly implemented for REST operations but fail in the specialized transport protocol context.
The operational impact of this vulnerability is severe as it allows for unauthorized data exfiltration from remote clusters without detection. A malicious actor could potentially access sensitive information across all indices within a remote cluster, depending on their API key permissions. The requirement for specific parameters including index ID, shard ID, and document ID suggests that this is not a broad unrestricted access but rather a targeted privilege escalation within the transport protocol layer. Organizations using Elasticsearch's remote cluster security features in their beta implementations face significant risk of data breaches, particularly in environments where multiple clusters are interconnected and sensitive data is stored. The fact that this affects only the custom transport protocol means that REST API users are protected, but transport protocol users remain vulnerable, creating an asymmetric security landscape within the same system.
Mitigation strategies for CVE-2024-23451 should prioritize immediate upgrade to Elasticsearch version 8.13.0 or later where the vulnerability has been addressed. Organizations should also implement network-level controls to restrict access to the custom transport protocol endpoints where possible, particularly in environments where the remote cluster security feature is enabled. Security monitoring should be enhanced to detect unusual patterns in transport protocol usage, especially when API keys are used in conjunction with specific index, shard, and document identifiers. The vulnerability aligns with CWE-284, which addresses improper access control in software systems, and maps to ATT&CK technique T1071.004 for application layer protocol usage. Administrators should review and audit all API key permissions for remote cluster configurations, ensuring that least privilege principles are applied and that unnecessary access to remote cluster resources is minimized. Additionally, organizations should consider disabling the beta Remote Cluster Security feature until proper authorization controls have been validated in production environments.