What is the FASTEST way to prevent the sensitive data from being exposed?
Download the data from the existing S3 bucket to a new EC2 instance. Then delete the data from the S3 bucket. Re-encrypt the data with a client-based key. Upload the data to a new S3 bucket.
Block access to the public range of S3 endpoint IP addresses by using a host-based firewall. Ensure that internet-bound traffic from the affected EC2 instance is routed through the host-based firewall.
Revoke the IAM role’s active session permissions. Update the S3 bucket policy to deny access to the IAM role. Remove the IAM role from the EC2 instance profile.
Disable the current key. Create a new KMS key that the IAM role does not have access to, and re-encrypt all the data with the new key. Schedule the compromised key for deletion.
Explanations:
Downloading and re-encrypting the data with a client-based key and uploading it to a new S3 bucket is a time-consuming process. It does not immediately prevent access to the data while addressing the potential vulnerability.
Blocking public IP ranges via a host-based firewall only addresses internet-bound traffic. It does not prevent the compromised EC2 instance from accessing the KMS key or the S3 bucket directly, which is the immediate concern.
Revoking the IAM role’s active session permissions, updating the S3 bucket policy to deny access, and removing the IAM role from the EC2 instance profile immediately prevents the instance from accessing sensitive data without needing to shut down the EC2 instance.
Disabling the KMS key and creating a new one addresses the encryption aspect, but it requires re-encrypting data and does not immediately prevent access to sensitive data from the compromised instance. Additionally, it could result in potential downtime.
I rate that the answer is:
Revoke the IAM role’s active session permissions. Update the S3 bucket policy to deny access to the IAM role. Remove the IAM role from the EC2 instance profile.