The Hidden Cost of Manual IAM Review
The Hidden Cost of Manual IAM Review Most teams don't track how long they spend reviewing IAM policies. When I started measuring it on my own team, the numbers were worse than I expected. A thorough manual review of one IAM policy takes 10 to 15 minutes. Not a quick scan. A real review: read every statement, trace every cross-account trust, verify every condition key, check for privilege escalation paths, confirm the resource ARNs match what you think they should. At 4 engineers touching IAM once a week, that's 4 hours a month. 48 hours a year of senior engineers reading JSON documents. And that's the optimistic case. Add a security incident. Add an audit. Add the emergency Friday-afternoon policy change that needs review before deploy. The real number is higher. What manual review misses The problem isn't just the time. It's that humans are bad at repetitive structured-data review, especially under time pressure. Here are the things I've seen slip through manual IAM reviews on production systems: iam:PassRole with no condition. This is the big one. PassRole lets a principal pass a role to a service — and if there's no iam:PassedToService condition, that role can be passed to any service that accepts roles. Including services the attacker controls. The reviewer saw the action, mentally categorized it as "role stuff," and moved on. It was statement 47 of 52 — the reviewer had already been reading policies for 40 minutes. Wildcard resource with sensitive actions. s3:* on Resource: "*" is obvious. s3:GetObject on "arn:aws:s3:::*-backup/*" with a wildcard in the bucket name — that's subtle. The reviewer reads it as "restricted to backup buckets" and moves on. But the wildcard means any bucket ending in -backup , including ones in other accounts if cross-account access is configured. Missing aws:SourceArn on Lambda invocation permissions. When you grant another service permission to invoke your Lambda function, you need aws:SourceArn to prevent the confused deputy