Strengthening Identity Synchronisation with Entra ID’s Application-Based Authentication

Identity synchronisation between on-premises Active Directory and Entra ID (formerly Azure AD) is a cornerstone of modern hybrid identity architectures. Traditionally, synchronisation relied on username/password-based service accounts—a practice that, while functional, introduced risks such as credential theft and stale password rotations. Microsoft’s new Application-Based Authentication (ABA) for Entra Connect Sync addresses these concerns. Here’s how to plan, deploy, and operate ABA for a more secure identity perimeter.

Why Move to ABA?

ABA leverages OAuth 2.0 client credentials, meaning Entra Connect Sync uses a service principal with certificate-based authentication instead of a password. This shift reduces the attack surface by:

• Eliminating long-lived passwords stored on synchronization servers.

• Enabling tighter control via Azure AD conditional access and managed identities.

• Simplifying compliance audits, with clear issuance and rotation records for certificates.

Migrating to Application-Based Authentication for Entra Connect Sync transforms your hybrid identity foundation. It replaces risky password storage with robust certificate management, aligns with Zero Trust principles, and simplifies compliance. By carefully planning, validating in a staging environment, and automating certificate lifecycle, organizations can fortify identity synchronisation, ensuring users enjoy seamless access without sacrificing security.