CVE-2021-37759 in Graylog
Summary
by MITRE • 08/01/2021
A Session ID leak in the DEBUG log file in Graylog before 4.1.2 allows attackers to escalate privileges (to the access level of the leaked session ID).
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Analysis
by VulDB Data Team • 08/06/2021
The vulnerability identified as CVE-2021-37759 represents a critical session management flaw within the Graylog open-source log management platform. This issue affects versions prior to 4.1.2 and stems from improper handling of session identifiers within debug logging mechanisms. The flaw enables attackers to obtain valid session IDs through exposure in log files, creating a direct pathway for unauthorized privilege escalation. The vulnerability operates at the intersection of insecure logging practices and session management security controls, fundamentally undermining the authentication and authorization mechanisms that protect Graylog instances.
The technical root cause of this vulnerability lies in the logging configuration where debug-level information containing session identifiers is written to log files without proper sanitization or access controls. When Graylog generates debug output, it inadvertently includes session tokens that should remain confidential and ephemeral. These session identifiers, once exposed in log files, can be harvested by attackers who gain access to the logging infrastructure or filesystem. The session ID leak creates a persistent threat vector where an attacker can reuse these identifiers to assume the identity and privileges of legitimate users, effectively bypassing normal authentication mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise. Attackers who obtain a valid session ID can access Graylog's administrative interfaces, view sensitive log data, modify configuration settings, and potentially exfiltrate or manipulate log information. This threat is particularly severe in environments where Graylog serves as a central logging solution for security monitoring and compliance reporting. The vulnerability can be exploited through various attack vectors including unauthorized file system access, log file enumeration, or through compromised systems that have access to the logging infrastructure. The exposure of session identifiers in debug logs represents a fundamental breakdown in the principle of least privilege and proper access control implementation.
Mitigation strategies for CVE-2021-37759 require immediate implementation of configuration changes and security hardening measures. Organizations should upgrade to Graylog version 4.1.2 or later where the vulnerability has been addressed through proper session ID handling in debug logging. Additionally, system administrators should implement strict access controls on log file directories, ensuring that only authorized personnel have read access to debug logs containing sensitive information. The implementation of log sanitization policies that prevent session identifiers from being written to debug output represents a critical defensive measure. Organizations should also consider implementing log monitoring and alerting systems to detect unusual access patterns or unauthorized attempts to read log files. This vulnerability aligns with CWE-200, which addresses improper exposure of sensitive information, and maps to ATT&CK technique T1563.002 for credential access through service logon tokens, emphasizing the critical nature of session management in enterprise security infrastructure.