CCSP Cloud Application Security Practice Question
A security architect is designing access controls for a cloud-based microservices application. Which approach best aligns with the principle of least privilege for service-to-service authentication?
⚠ Common exam trap
ISC2 often tests the misconception that shared secrets or broad IAM roles are acceptable for service-to-service communication, but the trap is that candidates overlook the need for per-service identity and cryptographic proof of identity, which mTLS uniquely provides.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement mutual TLS with unique certificates per service
Mutual TLS (mTLS) with unique certificates per service enforces least privilege by ensuring each microservice authenticates with a distinct identity, and access can be scoped to specific certificates. This prevents a compromised service from impersonating others, as each service has its own private key and certificate, and the TLS handshake requires both sides to present and validate certificates.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use long-lived bearer tokens
Why it's wrong here
Long-lived bearer tokens grant standing access until expiry or revocation, violating least privilege for service-to-service calls. It is tempting because bearer tokens are simple to issue and widely used, but short-lived tokens or workload identity federation with Microsoft Entra ID provide scoped, time-bound credentials instead.
- ✓
Implement mutual TLS with unique certificates per service
Why this is correct
Mutual TLS authenticates both ends using distinct per-service certificates, so each microservice proves its identity and only trusted peers connect. This enforces least privilege for service-to-service authentication rather than relying on shared secrets or network location.
- ✗
Assign IAM roles with broad permissions
Why it's wrong here
Broad IAM role permissions grant each microservice far more access than its function requires, directly violating least privilege and widening blast radius if one service is compromised. Roles are tempting because they provide scoped, credential-free authentication; a narrowly defined role per service, granting only its specific API actions, would be the correct choice.
- ✗
Use a shared API key across all services
Why it's wrong here
A shared API key gives every microservice identical credentials, so any single compromised service exposes the whole estate and no per-service audit trail exists. Shared keys are tempting for their simplicity in low-risk internal tooling; unique per-service identities with scoped permissions satisfy least privilege for service-to-service authentication.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CCSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CCSP exam.