CVE-2017-8442 in X-Pack Security
Summary
by MITRE
Elasticsearch X-Pack Security versions 5.0.0 to 5.4.3, when enabled, can result in the Elasticsearch _nodes API leaking sensitive configuration information, such as the paths and passphrases of SSL keys that were configured as part of an authentication realm. This could allow an authenticated Elasticsearch user to improperly view these details.
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Analysis
by VulDB Data Team • 10/24/2019
Elasticsearch X-Pack Security vulnerability CVE-2017-8442 represents a critical information disclosure flaw that emerged in versions 5.0.0 through 5.4.3 of the Elasticsearch platform. This vulnerability specifically targets the _nodes API endpoint which serves as a diagnostic interface for retrieving node-level information from the Elasticsearch cluster. When X-Pack security features are enabled, the system's configuration data becomes accessible through this API endpoint, creating a significant exposure point for sensitive operational details. The flaw manifests when authenticated users can leverage their legitimate access privileges to extract configuration parameters that should remain protected within the system's security boundaries.
The technical implementation of this vulnerability stems from inadequate access controls within the _nodes API implementation. The API response includes detailed configuration information about the Elasticsearch nodes, including file system paths where SSL certificates and keys are stored, as well as passphrase values used for encryption. This occurs because the API does not properly filter or sanitize the information returned based on user permissions or security contexts. The vulnerability directly maps to CWE-200, which defines information exposure through improper access control mechanisms, and represents a classic case of insufficient authorization checks within system interfaces. Attackers can exploit this by simply authenticating to the system and making requests to the _nodes endpoint, bypassing normal security boundaries that should prevent access to sensitive configuration data.
The operational impact of CVE-2017-8442 extends beyond simple information disclosure, as it provides attackers with critical assets necessary for further exploitation attempts. When an authenticated user can access SSL key paths and passphrases, they gain valuable intelligence for potential privilege escalation attacks or lateral movement within the network. The leaked information could enable attackers to impersonate services, decrypt communications, or even compromise the entire Elasticsearch cluster by using the exposed cryptographic materials. This vulnerability particularly affects environments where Elasticsearch serves as a critical data store for applications requiring high security standards, such as financial services, healthcare systems, or government agencies. The exposure of configuration details also violates fundamental security principles outlined in the NIST Cybersecurity Framework, specifically addressing the protection of sensitive information and the implementation of least privilege access controls.
Organizations affected by this vulnerability should immediately implement mitigations including upgrading to Elasticsearch versions 5.4.4 or later where the issue has been resolved through proper access control implementation. The fix involves restricting the information returned by the _nodes API to prevent exposure of sensitive configuration parameters while maintaining essential diagnostic functionality for legitimate administrative purposes. Security teams should also conduct comprehensive audits of their Elasticsearch deployments to identify any potential exploitation attempts and ensure that access controls are properly configured across all X-Pack security features. Additional mitigations include implementing network segmentation to limit access to Elasticsearch clusters, enforcing strict authentication requirements, and monitoring for unusual API access patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper API security design and aligns with ATT&CK technique T1083, which covers discovery of system information through API calls and diagnostic interfaces, emphasizing the need for robust access control mechanisms at all system interfaces.