Principle of Least Privilege IAM
Explain least privilege for cloud IAM. Give an example of a bad vs good policy for an app reading one S3 prefix.
Answers use simple, clear English.
Quick interview answer
Grant only the permissions required for the job, on the smallest resource scope, for the shortest time. Bad: s3:* on *. Good: s3:GetObject on arn:aws:s3:::bucket/app/* bound to a role assumed by that workload.
Detailed answer
Grant only the permissions required for the job, on the smallest resource scope, for the shortest time. Bad: s3:* on *. Good: s3:GetObject on arn:aws:s3:::bucket/app/* bound to a role assumed by that workload. Prefer roles over long-lived access keys. Privilege creep happens when policies are copied and never reviewed.
Full explanation
Privilege creep happens when policies are copied and never reviewed.
Real example & use case
CI job role can push only to the ECR repo for that service, not delete clusters.
Pros & cons
Pros: limits blast radius of leaks. Cons: tighter policies need better packaging/tooling for developers.