CVE-2021-20191 in Ansible
Summary
by MITRE • 05/27/2021
A flaw was found in ansible. Credentials, such as secrets, are being disclosed in console log by default and not protected by no_log feature when using those modules. An attacker can take advantage of this information to steal those credentials. The highest threat from this vulnerability is to data confidentiality. Versions before ansible 2.9.18 are affected.
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Analysis
by VulDB Data Team • 01/23/2025
This vulnerability resides in the ansible automation platform where sensitive credential information is being inadvertently exposed through console logging mechanisms. The flaw specifically affects the handling of secrets and credentials within ansible modules, where the no_log feature fails to properly protect sensitive data during execution. When ansible modules process credentials, the system logs these values to console output without adequate sanitization, creating a critical exposure point for attackers seeking to harvest authentication tokens, passwords, or other confidential information. The vulnerability represents a significant weakness in ansible's security architecture, particularly concerning data confidentiality as identified by the threat assessment.
The technical implementation of this flaw stems from insufficient input validation and output sanitization within ansible's logging subsystem. When modules execute commands that involve sensitive data, the logging mechanism does not properly filter or mask credential information before writing to console logs. This behavior violates fundamental security principles and creates an attack surface where adversaries can capture credential information from log files or console output streams. The vulnerability is particularly concerning because it operates at the core logging functionality of the automation platform, affecting all ansible modules that handle sensitive data. The no_log parameter, which should prevent credential exposure, fails to function correctly in these scenarios, leaving the system vulnerable to credential theft through simple log inspection.
The operational impact of this vulnerability extends beyond simple credential exposure, as it fundamentally undermines the security posture of organizations relying on ansible for automation tasks. Attackers can exploit this flaw by monitoring console output, examining log files, or intercepting output streams to extract authentication credentials, API keys, and other sensitive information. This exposure creates a persistent threat vector that can lead to unauthorized access to systems, data breaches, and lateral movement within network environments. The vulnerability affects organizations using ansible versions prior to 2.9.18, making it particularly relevant for enterprises maintaining older automation infrastructure. The confidentiality impact is rated highest because stolen credentials can enable attackers to escalate privileges, access restricted systems, and compromise entire infrastructure domains.
Organizations should implement immediate mitigations including upgrading to ansible version 2.9.18 or later where the vulnerability has been addressed. System administrators must also review existing ansible playbooks and configurations to ensure proper implementation of no_log directives and additional logging controls. Security teams should establish monitoring procedures to detect unauthorized credential exposure in log files and implement comprehensive log sanitization policies. The vulnerability aligns with CWE-209, which addresses information exposure through logging, and maps to ATT&CK technique T1552.001 for credentials in files and T1078 for valid accounts. Additional protective measures include implementing centralized logging with proper access controls, regular log audits, and network monitoring to detect credential harvesting attempts. Organizations should also consider implementing privilege separation and least-privilege principles to minimize the impact of credential compromise, while establishing incident response procedures specifically designed to address credential exposure events.