The security of Azure Arc-enabled servers is a shared responsibility. Microsoft is responsible for securing the cloud service that stores system metadata, protecting privacy, documenting optional security features, publishing regular agent updates, managing RBAC access, and securing the server infrastructure. Users are responsible for securing the server itself, managing credentials, determining the application of security features, and ensuring compliance with legal and internal policies.

The Azure Connected Machine agent acts as an enablement platform that connects your machine to Azure. It establishes a relationship with your Azure subscription, provides a managed identity for authentication, enables additional capabilities through extensions, and enforces settings on your server. The agent is essential for relaying data and actions between your managed server and Azure.

For Tier 0 assets, it is recommended to use a dedicated Azure subscription to minimize access and closely monitor permissions. You should also disable unnecessary management features, such as remote access capabilities and the extension manager, unless they are needed. Implementing an extension allowlist can help restrict the use of extensions to only those that meet your security requirements.