CVE-2018-3827 in Elasticsearch repository-azure Plugin
Summary
by MITRE
A sensitive data disclosure flaw was found in the Elasticsearch repository-azure (formerly elasticsearch-cloud-azure) plugin. When the repository-azure plugin is set to log at TRACE level Azure credentials can be inadvertently logged.
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Analysis
by VulDB Data Team • 03/25/2020
The vulnerability identified as CVE-2018-3827 represents a critical sensitive data disclosure flaw within the Elasticsearch ecosystem, specifically affecting the repository-azure plugin formerly known as elasticsearch-cloud-azure. This plugin facilitates integration between Elasticsearch and Microsoft Azure cloud storage services, enabling organizations to use Azure blob storage as a repository for Elasticsearch snapshots and backups. The flaw manifests when administrators configure the plugin to operate at TRACE logging level, which is typically reserved for detailed debugging purposes during development or troubleshooting phases. When TRACE level logging is enabled, the plugin inadvertently captures and outputs Azure authentication credentials to log files, creating a significant security risk that can compromise cloud infrastructure access.
The technical nature of this vulnerability stems from improper handling of authentication credentials within the logging mechanism of the repository-azure plugin. The flaw occurs because the plugin does not adequately sanitize or filter sensitive information before writing log entries at TRACE level. According to CWE-532, this vulnerability maps directly to the weakness of inserting information into log files, where sensitive data is written to logs without proper filtering or obfuscation. The plugin's logging subsystem processes Azure credentials as regular log data without recognizing their sensitive nature, resulting in credential exposure within log files that may be accessible to unauthorized users or systems with appropriate file permissions. This represents a classic case of insufficient logging sanitization and credential handling practices that violates fundamental security principles for protecting authentication information.
The operational impact of CVE-2018-3827 extends beyond simple credential exposure, as it can lead to complete cloud infrastructure compromise and unauthorized access to sensitive data stored within Elasticsearch clusters. When Azure credentials are logged, attackers who gain access to system logs can extract these credentials and use them to access Azure storage accounts, potentially gaining access to all data stored in those repositories including Elasticsearch snapshots, backup data, and associated metadata. This vulnerability particularly affects organizations using Elasticsearch in production environments where TRACE level logging might be enabled for troubleshooting purposes, or where log files are not properly secured or rotated. The risk is exacerbated when these log files are stored in locations accessible to multiple users or when automated systems process log files without proper access controls, creating multiple attack vectors for credential compromise.
Organizations should implement immediate mitigations to address this vulnerability by first ensuring that TRACE level logging is disabled or properly secured when using the repository-azure plugin. According to ATT&CK technique T1567.002, adversaries can leverage exposed credentials to move laterally within cloud environments, making it crucial to prevent credential exposure at the source. System administrators should configure appropriate log file permissions, implement log rotation policies, and ensure that sensitive information is not stored in plain text within log files. The recommended approach involves setting logging levels to WARN or ERROR only, which prevents the exposure of sensitive data while maintaining necessary operational visibility. Additionally, organizations should implement monitoring solutions that can detect and alert on the presence of credential-like information in log files, and establish regular security audits to identify and remediate similar issues across other plugins and components within their Elasticsearch deployments.