CVE-2018-10855 in Ansible
Summary
by MITRE
Ansible 2.5 prior to 2.5.5, and 2.4 prior to 2.4.5, do not honor the no_log task flag for failed tasks. When the no_log flag has been used to protect sensitive data passed to a task from being logged, and that task does not run successfully, Ansible will expose sensitive data in log files and on the terminal of the user running Ansible.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability described in CVE-2018-10855 represents a critical security flaw in Ansible automation software versions prior to 2.5.5 and 2.4.5. This issue specifically targets the handling of the no_log task flag mechanism that is designed to protect sensitive information during automation processes. The no_log flag serves as a fundamental security control within Ansible's architecture, intended to prevent sensitive data such as passwords, API keys, or confidential parameters from being exposed in logs or terminal output when tasks execute successfully. However, this vulnerability creates a significant bypass in the security model by failing to properly respect the no_log directive when tasks encounter failures, thereby undermining the intended protection mechanisms.
The technical flaw manifests in the improper logging behavior of Ansible's task execution engine when failures occur. Normally, Ansible's no_log functionality should suppress all output related to variables and parameters passed to tasks, ensuring that even failed operations do not expose sensitive information in log files or console output. The vulnerability arises from a code path that does not properly implement the no_log flag during error handling scenarios, causing the system to log complete task parameters and sensitive data even when the task fails. This behavior directly violates the principle of least privilege and data protection that should govern all automation platforms handling confidential information.
The operational impact of this vulnerability extends beyond simple information disclosure, creating substantial risks for organizations relying on Ansible for infrastructure automation and configuration management. When tasks fail due to authentication errors, network issues, or configuration problems, the exposure of sensitive data through logs and terminal output provides attackers with valuable information for further exploitation attempts. This vulnerability particularly affects environments where Ansible is used for deploying applications with database credentials, API tokens, or other security-sensitive parameters, as failed deployments could inadvertently expose these credentials to unauthorized parties. The exposure occurs both in persistent log files and in real-time terminal output, amplifying the potential attack surface and making the vulnerability particularly dangerous in production environments.
Organizations should prioritize immediate remediation by upgrading to Ansible versions 2.5.5 or 2.4.5, which contain the necessary patches to properly enforce the no_log flag behavior for failed tasks. The mitigation strategy should also include comprehensive review of existing automation scripts to ensure proper implementation of the no_log directive, combined with enhanced monitoring of log files for any suspicious activity or unexpected data exposure patterns. Security teams should implement additional controls such as log file access restrictions, regular audit of automation task outputs, and enhanced monitoring for credential exposure in both persistent logs and real-time execution environments. This vulnerability highlights the critical importance of proper error handling and logging practices in automation platforms, as the failure to respect security controls during error scenarios can create significant exposure points that attackers can exploit to gain unauthorized access to sensitive information. The issue aligns with CWE-200, which addresses improper exposure of sensitive information, and represents a clear violation of security best practices outlined in various security frameworks including the ATT&CK framework's credential access and defense evasion categories where such information disclosure vulnerabilities can enable further compromise of systems and data.