CVE-2018-3826 in Elasticsearch
Summary
by MITRE
In Elasticsearch versions 6.0.0-beta1 to 6.2.4 a disclosure flaw was found in the _snapshot API. When the access_key and security_key parameters are set using the _snapshot API they can be exposed as plain text by users able to query the _snapshot API.
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Analysis
by VulDB Data Team • 03/25/2020
The vulnerability identified as CVE-2018-3826 represents a critical information disclosure flaw within Elasticsearch versions ranging from 6.0.0-beta1 through 6.2.4. This security weakness specifically affects the _snapshot API functionality and exposes sensitive authentication credentials through improper handling of access_key and security_key parameters. The flaw arises from the system's failure to adequately protect credential information during API operations, creating a potential vector for unauthorized access to sensitive data. This vulnerability directly impacts organizations relying on Elasticsearch for data storage and retrieval, particularly those implementing snapshot functionality for backup and recovery operations.
The technical implementation of this vulnerability stems from the _snapshot API's inadequate handling of authentication parameters during snapshot repository registration and management operations. When users configure snapshot repositories using the _snapshot API, they provide access_key and security_key parameters that are subsequently stored within the Elasticsearch system. However, the system fails to properly sanitize or encrypt these parameters during subsequent API queries, resulting in their exposure as plain text in API responses. This design flaw allows any authenticated user with access to query the _snapshot API to retrieve these sensitive credentials, effectively undermining the security controls designed to protect authentication information. The vulnerability operates under CWE-200, which categorizes information exposure issues, and represents a specific instance of improper information protection where sensitive data is unintentionally disclosed.
The operational impact of this vulnerability extends beyond simple credential exposure, as it fundamentally compromises the security posture of Elasticsearch deployments. Attackers who can query the _snapshot API gain access to plaintext credentials that may be used to authenticate against external storage systems such as s3 buckets, azure storage accounts, or other cloud-based repositories. This exposure enables unauthorized data access, potential data exfiltration, and privilege escalation attacks within the affected infrastructure. The vulnerability is particularly dangerous in multi-tenant environments or when organizations implement automated backup solutions, as it provides attackers with the means to access backup repositories and potentially compromise entire data ecosystems. The exposure of these credentials through API responses creates a persistent threat vector that remains active until the vulnerability is patched or mitigated.
Organizations affected by this vulnerability should immediately implement several mitigation strategies to protect their Elasticsearch deployments. The primary remediation involves upgrading to Elasticsearch versions 6.3.0 or later where this vulnerability has been addressed through proper credential handling and sanitization. Additionally, administrators should implement strict access controls and privilege management to limit who can query the _snapshot API, ensuring that only authorized personnel have access to these sensitive operations. Network segmentation and firewall rules should be configured to restrict access to Elasticsearch endpoints, particularly those handling sensitive operations. The implementation of proper logging and monitoring solutions can help detect unauthorized access attempts to snapshot APIs. Organizations should also conduct thorough credential rotation procedures for any snapshot repositories that may have been exposed, ensuring that all potentially compromised credentials are invalidated and replaced with new secure values. This vulnerability aligns with ATT&CK technique T1552.001, which covers "Credentials: Credentials In Files," as the exposure occurs through API responses that inadvertently disclose sensitive information.