CVE-2017-8441 in X-Pack Security
Summary
by MITRE
Elastic X-Pack Security versions prior to 5.4.1 and 5.3.3 did not always correctly apply Document Level Security to index aliases. This bug could allow a user with restricted permissions to view data they should not have access to when performing certain operations against an index alias.
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Analysis
by VulDB Data Team • 10/13/2019
The vulnerability described in CVE-2017-8441 represents a critical access control flaw within the Elastic X-Pack Security module that affected versions prior to 5.4.1 and 5.3.3. This issue specifically targets the implementation of Document Level Security (DLS) mechanisms that are designed to restrict user access to specific documents within Elasticsearch indices. The flaw occurs when users interact with index aliases rather than direct indices, creating a pathway for privilege escalation and unauthorized data access. The vulnerability demonstrates a fundamental breakdown in the security model's enforcement mechanisms, where the system fails to properly validate access permissions when operations are performed against aliased indices.
The technical implementation of this vulnerability stems from how Elastic's security layer processes requests when they involve index aliases rather than direct index references. When a user performs operations against an index alias, the system should enforce the same access controls that would apply to the underlying indices. However, the bug in the affected versions causes the Document Level Security filters to be bypassed or incorrectly applied when alias operations are processed. This creates a scenario where users with limited permissions can potentially access data that should be restricted based on their role assignments and security policies. The flaw specifically manifests when certain operations are executed against index aliases, where the security context is not properly maintained across the alias resolution process.
The operational impact of this vulnerability is significant for organizations relying on Elastic's security features to protect sensitive data. Attackers who can exploit this vulnerability gain unauthorized access to restricted data that should be protected by Document Level Security policies. This could result in data breaches, compliance violations, and exposure of confidential information that organizations depend on Elastic to protect. The vulnerability affects the core security model of the system, undermining the trust in the access control mechanisms that administrators rely upon to protect their data assets. Organizations using Elastic Stack for log management, monitoring, and analytics could face serious consequences if this vulnerability is exploited, particularly in environments with strict data governance requirements.
Organizations should immediately upgrade to Elastic X-Pack Security versions 5.4.1 or 5.3.3 to remediate this vulnerability. The upgrade process should include thorough testing to ensure that existing security policies and access controls continue to function correctly after the update. Additionally, administrators should conduct comprehensive audits of their current access control configurations to identify any potential misuse of the vulnerability. The mitigation strategy should also include monitoring for unusual access patterns that might indicate exploitation attempts. Security teams should implement enhanced logging and alerting mechanisms to detect unauthorized access attempts and maintain detailed records of all index alias operations for forensic analysis. This vulnerability aligns with CWE-284 Access Control Issues and represents a specific implementation weakness in the ATT&CK technique T1078 Valid Accounts, where attackers leverage legitimate access to exploit security controls through misconfigurations.