How to Grant AWS Auditors Secure Access Using Cross-Account IAM Roles

Companies often grant external auditors AWS access by creating IAM users or identity provider accounts, but neither approach is necessary or secure. AWS supports a cross-account IAM role mechanism that allows auditors to assume a temporary role in your account without any credentials ever changing hands. The setup relies on four safeguards: a trust policy tied to the auditor's AWS account, an External ID condition to prevent unauthorized access, time-limited STS session credentials, and full CloudTrail logging of every action taken. Permissions are restricted to read-only managed policies, with optional billing access and a supplementary policy covering services like GuardDuty and Security Hub. A developer has published two CloudFormation templates on GitHub — one for a single account and one for an entire AWS Organization — each deployable in roughly five minutes.