iam

AWS IAM policy evaluation combines explicit Deny overrides, Service Control Policies, resource-based policies, and identity-based policies to calculate effective access. Understanding this layered evaluation logic prevents unintended privilege escalation.

Writing a least-privilege IAM policy for cross-account access requires pairing a minimal trust policy with a scoped identity policy. This restricts cross-account role assumption to specific resources and actions, reducing broad access vulnerabilities.

Validating IAM policies and trust policies is best achieved using Access Analyzer. It reviews your permissions against external access and least-privilege patterns to detect resources shared outside your AWS account zone of trust.

You need permission boundaries and Service Control Policies when delegating AWS IAM administration safely. Boundaries cap maximum permissions an identity can receive, while SCPs guard organizational units, ensuring role-based access control stays within limits.

AWS Access Analyzer supports validating explicit Deny and Allow logic within identity policies and resource policies. It evaluates your IAM configurations against external access patterns to confirm effective permissions match your intended access control.