An organization in AWS Organizations has an Amazon S3 bucket in one account that is currently public. A security engineer must make the bucket private and ensure it cannot be made public in the future. Which solution meets these requirements?

The correct solution involves two steps: first, immediately making the bucket private, and second, preventing future public access. Enabling S3 Block Public Access on the bucket directly makes it private by blocking all public access. To prevent users from disabling this critical security control, an AWS Organizations Service Control Policy (SCP) is used. Denying s3:PutPublicAccessBlock at the Organizational Unit (OU) level prevents any account within that OU from modifying or disabling the S3 Block Public Access settings, thus ensuring the bucket remains private. Incorrect options: Using KMS encryption and denying s3:GetObject does not inherently make the bucket private; it only encrypts objects and restricts read access, but the bucket itself could still be configured for public access. Denying s3:GetObject in an SCP restricts read access but doesn't prevent the bucket from being made public or having its public access settings changed. S3 Object Lock is for data immutability (preventing deletion or modification of objects), not for controlling public access settings.