What is a Service Principal in Microsoft 365?

A Service Principal in Microsoft 365 is an identity used to authenticate and authorize applications or automation scripts to access Microsoft services. It acts as a bridge between an application and your Azure AD tenant, enabling secure access to resources without requiring user credentials.

Key Characteristics of a Service Principal

• Application Identity:
  • Represents an application in Azure AD for authentication.
  • Associated with a single tenant or multiple tenants in multi-tenant scenarios.
• Permissions:
  • Uses application permissions or delegated permissions to define what the application can access.
  • Permissions must be explicitly granted by an admin
• Secure Access:
  • Authenticates using a client secret or certificate, eliminating the need for user credentials.

Use Cases for Service Principals

• Application Integration: Allow third-party apps or custom-built solutions to interact with Microsoft 365.
• Automation: Run background tasks like sending emails or retrieving reports without user involvement.
• Secure API Access:: Enable PowerShell scripts or REST API calls to interact with Azure AD or Microsoft Graph.

How to Manage Service Principals

• Creation:: Register an application in Azure AD to automatically create its Service Principal.
• Permissions:: Assign and manage permissions via the Azure portal or PowerShell.

New-AzADServicePrincipal -DisplayName "MyApp"

• Audit:: Regularly review Service Principals and their permissions for security compliance.

Explore More

• Using New-MgServicePrincipal to Create Service Principal
• Using New-AzADServicePrincipal to Create Service Principal

Service Principals provide a secure and efficient way for applications to interact with your Microsoft 365 environment, ensuring seamless integration and automation.