Cloud IAM policy evaluation and effective permissions

Mechanism

Cloud authorization combines identity policies, resource policies, organizational controls, permission boundaries, session policies, and service-specific conditions. A visible allow statement is not the complete decision. In AWS, explicit deny and the intersection with limiting policies are especially important. Principal identity and request context determine which statements apply.

Practical method

Identify the account and active principal. Inventory attached and inline policies, boundaries, and relevant resource policies within the lab. Build a table of action, resource, and condition. Test the smallest read-only action that distinguishes an inferred permission from an assumption.

aws sts get-caller-identity
# Use only the credentials and account supplied by the challenge.

Interpreting evidence

A successful action validates one request context. A denial can originate from several policy layers, so preserve the action, resource, principal, and applicable conditions.

Pitfalls and limits

Wildcards in action and resource fields have different meanings. Cross-account access needs permissions on both sides in many cases. Session tags and source identity can change condition evaluation.