CVE-2018-17244 in Elasticsearch Security
Summary
by MITRE
Elasticsearch Security versions 6.4.0 to 6.4.2 contain an error in the way request headers are applied to requests when using the Active Directory, LDAP, Native, or File realms. A request may receive headers intended for another request if the same username is being authenticated concurrently; when used with run as, this can result in the request running as the incorrect user. This could allow a user to access information that they should not have access to.
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Analysis
by VulDB Data Team • 04/22/2020
The vulnerability identified as CVE-2018-17244 affects Elasticsearch Security versions 6.4.0 through 6.4.2 and represents a critical authentication bypass issue stemming from improper header handling during concurrent user authentication processes. This flaw specifically impacts environments utilizing Active Directory, LDAP, Native, or File realms for user authentication, creating a scenario where request headers intended for one user session can be incorrectly applied to another concurrent authentication request. The technical implementation error occurs within the request processing pipeline where header context management fails to properly isolate authentication contexts, leading to cross-contamination of authentication metadata between simultaneous user sessions.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential data exposure and unauthorized access to sensitive information. When combined with the run as functionality, which allows users to execute requests with elevated privileges under different user identities, the flaw becomes particularly dangerous as it can enable an authenticated user to impersonate other users and access data that should be restricted to specific authorized personnel. This creates a significant risk for organizations relying on Elasticsearch for storing sensitive data, including personal information, financial records, or proprietary business data. The vulnerability essentially allows for unauthorized privilege delegation where malicious actors could leverage concurrent authentication sessions to gain access to information they would normally be denied.
From a cybersecurity perspective, this vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1078 for valid accounts and privilege escalation. The flaw demonstrates a classic case of context leakage in multi-threaded authentication systems where shared resources are not properly isolated. The vulnerability exists due to inadequate synchronization mechanisms and header management within the authentication subsystem, allowing concurrent requests to interfere with each other's authentication context. Organizations using Elasticsearch with security features enabled are particularly at risk as this vulnerability can be exploited without requiring elevated privileges or specialized tools, making it a significant concern for enterprise security.
Mitigation strategies for CVE-2018-17244 include immediate deployment of Elasticsearch Security version 6.4.3 or later, which contains the necessary patches to address the header handling issue. Organizations should also implement additional monitoring for concurrent authentication patterns and unusual access requests that might indicate exploitation attempts. Network segmentation and strict access controls should be enforced to limit exposure, while regular security audits should verify that authentication contexts are properly isolated. The vulnerability underscores the importance of proper concurrent request handling in authentication systems and highlights the need for robust isolation mechanisms when managing multiple simultaneous user sessions, particularly in enterprise environments where data security and access control are paramount considerations.