Maester

Maester is an open-source PowerShell-based test automation framework designed to help administrators monitor and maintain the security configuration of Microsoft 365 and Entra ID environments. Created by Microsoft Product Manager Merill Fernando along with Security MVPs Fabian Bader and Thomas Naunheim, Maester provides over 140+ automated security tests that validate tenant configurations against industry best practices, MITRE ATT&CK framework, Microsoft security baselines, and CISA guidelines. The tool natively integrates the Entra ID Security Config Analyzer (EIDSCA) and includes extensive Conditional Access policy testing capabilities. Maester generates comprehensive HTML reports with detailed remediation guidance for failed tests, making it easy to understand and fix security misconfigurations. It supports continuous monitoring through GitHub Actions and Azure DevOps pipelines using workload identity federation for secure authentication. The framework is built on top of Pester, the popular PowerShell testing framework, allowing administrators to write custom tests that encode their organization-specific security policies. Maester is particularly valuable for MSPs managing multiple Microsoft 365 tenants, offering automated security assessments and compliance validation at scale.