Service-to-service authorization is the enforcement of what one authenticated service is allowed to do when calling another service. It matters because authentication alone is not enough if every internal service can ask every other service for anything.
What is Service-to-Service Authorization?
This control defines allowed actions, resources, scopes, and trust relationships between machine identities. It is central to zero-trust architecture and to reducing blast radius after service compromise.
What Service-to-Service Authorization Commonly Supports
Common uses include internal API security, workload segmentation, zero-trust service design, and least-privilege enforcement.
Service-to-Service Authorization vs. Authenticated but Overtrusted Service Access
Service-to-service authorization limits actions after identity is verified. Overtrusted access authenticates the caller but still grants too much permission.
Frequently Asked Questions
Why is service authorization important internally?
Because many breaches spread through overly trusted internal service relationships after initial compromise.
How is it different from service authentication?
Authentication answers who the service is. Authorization answers what that service may do.
Related Cybersecurity Terms
- Machine-to-Machine Authentication
- Internal Attack Surface
- Least Privilege Access
- Broken Function Level Authorization (BFLA)
