A company uses an organization in AWS Organizations to manage multiple AWS accounts.

Aservice control policyis the right control because SCPs apply guardrails at the AWS Organizations level across member accounts. AWS documentation states that SCPs do not grant permissions; instead, they define the maximum permissions available in member accounts. An explicit deny oniam:CreateUserapplied through an SCP prevents new IAM users from being created in those accounts, while existing IAM users can continue to operate within the permissions they already have, subject to the SCP. IAM policies and permissions boundaries are not the best organization-wide control for this requirement because they are not the same centralized account-level guardrail mechanism that SCPs provide. Therefore, the correct answer is to use anSCP denying iam:CreateUser. (AWS Documentation)

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