AWS IAM Security Best Practices — Why Over-Permissive Access Is Your Biggest Cloud Risk

TLDR: I audited a Series A startup's AWS account last year. Seven developers, all with AdministratorAccess. Three inactive accounts from people who'd left the company — still enabled, still with full permissions. Root account with no MFA. No API key rotation in 18 months. This is not unusual. It's the norm. IAM misconfiguration is the number one cloud attack vector — and fixing it costs nothing but time. Here's exactly what to fix. What IAM Is and Why It's the Foundation of Cloud Security AWS Identity and Access Management (IAM) is the system that controls who can do what in your AWS account. Every API call, every console login, every automated process that touches your cloud infrastructure goes through IAM. If IAM is misconfigured, every other security control is undermined — an attacker with the right IAM credentials can read your data, modify your infrastructure, delete your backups, and exfiltrate everything you've built. According to the CrowdStrike 2025 Global Threat Report , clo