CVE-2023-6687 in Elastic
Summary
by MITRE • 12/12/2023
An issue was discovered by Elastic whereby Elastic Agent would log a raw event in its own logs at the WARN or ERROR level if ingesting that event to Elasticsearch failed with any 4xx HTTP status code except 409 or 429. Depending on the nature of the event that Elastic Agent attempted to ingest, this could lead to the insertion of sensitive or private information in the Elastic Agent logs. Elastic has released 8.11.3 and 7.17.16 that prevents this issue by limiting these types of logs to DEBUG level logging, which is disabled by default.
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Analysis
by VulDB Data Team • 01/04/2024
The vulnerability identified as CVE-2023-6687 represents a significant information disclosure risk within Elastic Agent's logging mechanism that operates under the Common Weakness Enumeration framework as a CWE-200 Information Exposure. This flaw manifests when the Elastic Agent encounters ingestion failures while attempting to send data to Elasticsearch, specifically triggering warning or error level logging of raw events when HTTP status codes in the 4xx range are returned except for 409 (Conflict) and 429 (Too Many Requests). The root cause lies in the agent's insufficient sanitization of event data before logging, creating a scenario where sensitive information becomes inadvertently exposed through the logging system.
The operational impact of this vulnerability extends beyond simple information leakage, as it creates potential attack vectors for adversaries seeking to extract confidential data from system logs. When Elastic Agent processes events containing personally identifiable information, corporate secrets, or other sensitive data, the logging mechanism fails to properly filter or sanitize this content before writing it to log files at WARN or ERROR levels. This behavior directly violates security best practices and could enable attackers to gain unauthorized access to private information through log file enumeration or unauthorized access to the logging infrastructure. The vulnerability affects Elastic Agent versions prior to 8.11.3 and 7.17.16, representing a critical gap in the system's defensive posture.
The exploitation of this vulnerability aligns with tactics described in the MITRE ATT&CK framework under the T1567.002 technique for "Exfiltration Over Web Service" and T1562.001 for "Disable or Modify Tools" as attackers could potentially leverage the exposed logs to extract sensitive data or use the information to craft more targeted attacks. The fix implemented by Elastic addresses this through a fundamental change in logging behavior, specifically reducing the verbosity of these particular log entries to DEBUG level, which remains disabled by default. This mitigation strategy effectively prevents the unintended exposure of sensitive information while maintaining the system's operational integrity for legitimate debugging purposes.
Organizations utilizing Elastic Agent must prioritize immediate patching to version 8.11.3 or 7.17.16 to eliminate this exposure risk, as the default logging configuration could otherwise allow sensitive data to persist in system logs accessible to unauthorized parties. The remediation approach demonstrates proper security engineering practices by implementing defense-in-depth measures that prevent sensitive information leakage while maintaining operational visibility through controlled debugging mechanisms. This vulnerability serves as a critical reminder of the importance of proper input sanitization and logging security controls within security tooling, particularly in environments where sensitive data processing is commonplace.