Zero Trust Beyond Identity: Securing Microservices & APIs

Zero Trust is often equated solely with identity and device verification, yet the modern cloud-native era demands that organisations also consider service-to-service trust. Australian companies increasingly deploy microservices architectures—often on AKS or App Service—and unsecured APIs can become gateways for lateral movement.

Why Service Trust Matters

APIs expose business logic and data. A stolen service principal or misconfigured managed identity can let an attacker pivot from a compromised front-end service to back-end databases. Awareness of this risk begins with understanding that certificates, keys and tokens require the same governance as user credentials.

Principles for API Security

• Least Privilege for Service Principals: Assign narrowly scoped roles in Entra ID. If a microservice only needs read access to a storage account, avoid granting broader “Contributor” rights.

• Short-Lived Tokens & Certificate Rotation: Use managed identities wherever possible; for scenarios requiring certificates, implement automated rotation—Azure Key Vault can trigger events when certificates near expiry. Awareness campaigns should note that token leakage is a major risk if lifetimes exceed 1–2 hours.

• API Gateway Enforcement: Centralise ingress through Azure API Management or similar gateways, enforcing rate limiting, payload inspection and mutual TLS if supported. Communicate that an API gateway is more than a performance enhancer—it’s a chokepoint for security.

Observability & Threat Detection

Log all API calls—method, origin IP, response codes—and feed into Sentinel. Create alerts for anomalous patterns: 500 errors triggered by unexpected payload sizes or sudden spikes in GET requests to sensitive endpoints. Awareness for dev teams should emphasise that structured logging is not optional; it’s a foundational requirement for detecting abuse.

Cultural Shift for Dev Teams

Securing microservices requires developers to think in threat models. Incorporate short “security huddles” at the start of each sprint to ask: “What could go wrong if someone tampers with this endpoint?” Embedding this mindset shifts security from “someone else’s problem” to a shared responsibility.