CVE-2017-8447 in X-Pack Security
Summary
by MITRE
An error was found in the X-Pack Security 5.3.0 to 5.5.2 privilege enforcement. If a user has either 'delete' or 'index' permissions on an index in a cluster, they may be able to issue both delete and index requests against that index.
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Analysis
by VulDB Data Team • 11/20/2019
The vulnerability described in CVE-2017-8447 represents a critical privilege escalation flaw within the X-Pack Security module of Elasticsearch versions 5.3.0 through 5.5.2. This issue stems from an improper implementation of access control mechanisms that fails to properly enforce the principle of least privilege. The vulnerability specifically affects the privilege enforcement system that governs user permissions within distributed search clusters, creating a scenario where users with limited permissions can potentially bypass security boundaries and execute unauthorized operations.
The technical flaw manifests in the way Elasticsearch processes and validates user permissions when interacting with indices. When a user possesses either delete or index permissions on a specific index, the system incorrectly grants them the ability to perform both delete and index operations against that same index. This represents a classic case of insufficient authorization checking where the system fails to properly distinguish between different types of operations that require separate permission levels. The flaw exists at the core of the privilege enforcement logic, allowing for privilege escalation through what should be distinct and separate permission sets.
The operational impact of this vulnerability is severe and far-reaching for organizations utilizing affected Elasticsearch versions. Attackers could exploit this weakness to gain unauthorized access to data manipulation capabilities beyond their intended permissions, potentially leading to data destruction, unauthorized modifications, or information disclosure. The vulnerability undermines the fundamental security model of the system by allowing users to perform operations they should not be authorized to execute, creating a pathway for both insider threats and external exploitation. Organizations relying on Elasticsearch for critical data storage and search operations face significant risk of data compromise and system integrity violations.
This vulnerability maps directly to CWE-284: Improper Access Control, which specifically addresses insufficient access control mechanisms that allow unauthorized users to access resources or perform operations. The issue also aligns with ATT&CK technique T1078: Valid Accounts, as it enables attackers to leverage existing legitimate user accounts to perform unauthorized actions. Additionally, the flaw demonstrates characteristics of T1485: Data Destruction, as users with elevated permissions could potentially destroy data through unauthorized delete operations. The vulnerability represents a failure in the security architecture's defense in depth principles, where multiple layers of protection should have prevented this unauthorized access escalation.
Organizations should immediately upgrade to Elasticsearch versions 5.5.3 or later, where this vulnerability has been properly addressed through enhanced privilege enforcement mechanisms. Administrators should review and audit existing user permissions to ensure that users only possess the minimum required access levels for their operational needs. Implementing additional monitoring and alerting systems can help detect unusual patterns of index operations that might indicate exploitation attempts. The fix involves strengthening the access control validation logic to properly enforce distinct permission boundaries between different operations, ensuring that delete and index permissions are treated as separate and distinct authorization requirements. Regular security assessments and penetration testing should be conducted to verify that access control mechanisms function as intended and that no similar privilege escalation vulnerabilities exist within the system.