What is Entra ID application base authentication?
Microsoft Entra ID application-based authentication (also known as app-based authentication) is a secure method for authenticating applications or services to Microsoft Entra ID (formerly Azure Active Directory). It leverages an application identity through the OAuth 2.0 client credentials flow, using certificate credentials or client secrets instead of traditional username/password combinations. This approach is ideal for service-to-service interactions, such as those in Microsoft Entra Connect (formerly Azure AD Connect), promoting passwordless security and reducing risks like credential exposure.
Key Concepts
- Application Identity: An app is registered in Entra ID as a service principal, assigned credentials (e.g., a certificate or client secret) for self-authentication, eliminating the need for user accounts.
- OAuth 2.0 Client Credentials Flow: The app presents its credentials to Entra ID to acquire an access token, enabling access to resources like Microsoft Graph APIs without user involvement.
- Passwordless Design: Certificates (preferred) or secrets minimize vulnerabilities associated with passwords, such as theft or rotation issues.
- Use Cases: Backend integrations (e.g., app-to-app communication), automation scripts, and hybrid identity sync via Microsoft Entra Connect, where it replaces legacy service accounts for syncing on-premises Active Directory with Entra ID.
Prerequisites
- Entra Connect version 2.5.76.0 or later (download from the Microsoft Entra admin center, not the Download Center).
- Administrative roles: Global Administrator or Hybrid Identity Administrator.
- For certificates: Self-signed or CA-issued, with non-exportable private keys (preferably in HSM/TPM); Windows Server 2016+ with TLS 1.2.
Locating the Application in Microsoft Entra ID
After enabling, the app is registered automatically as a single-tenant, non-Microsoft application. It won't appear with names like "Microsoft Entra ID Connect"—instead:
- Navigate to Microsoft Entra admin center > Enterprise applications > All applications.
- Search for "ConnectSyncProvisioning" to find it.
- For multiple servers: Each installation creates a unique app named "ConnectSyncProvisioning_[server name]", where [server name] is the Entra Connect server's hostname (e.g., "ConnectSyncProvisioning_ADConnectServer1").
- Launch the wizard and select Tasks > View or export current configuration.
- Application ID will be visible on the configuration
Benefits
- Security Boost: Automatic rotations (every 6 months) and hardware protection via TPM/HSM.
- Ease of Management: Reduces manual interventions; monitor via event logs (e.g., Event ID 1011 for expiration warnings).
- Alignment with Zero Trust: Supports Microsoft's passwordless initiatives.
Best Practices and Considerations
- Certificate Management: For BYOC, use RSA 2048-bit keys with SHA256; revoke via admin center if compromised.
- Monitoring: Use Azure Monitor for auth events; check logs for issues.
- Limitations: Service-to-service only—not for user sign-ins. Test in staging servers first.
- Troubleshooting: If not auto-configuring, ensure network access to Entra endpoints; manually rotate certificates via wizard if needed.