A. Create an Application Load Balancer with the existing EC2 instances as a target group. Create an AWS WAF web ACL containing rules that protect the application from this attack, then apply it to the ALB. Test to ensure the vulnerability has been mitigated, then redirect the Route 53 records to point to the ALB. Update security groups on the EC2 instances to prevent direct access from the internet.
B. Create an Amazon CloudFront distribution specifying one EC2 instance as an origin. Create an AWS WAF web ACL containing rules that protect the application from this attack, then apply it to the distribution. Test to ensure the vulnerability has been mitigated, then redirect the Route 53 records to point to CloudFront.
C. Obtain the latest source code for the platform and make the necessary updates. Test the updated code to ensure that the vulnerability has been mitigated, then deploy the patched version of the platform to the EC2 instances.
D. Update the security group that is attached to the EC2 instances, removing access from the internet to the TCP port used by the SQL database. Create an AWS WAF web ACL containing rules that protect the application from this attack, then apply it to the EC2 instances. Test to ensure the vulnerability has been mitigated, then restore the security group to the original setting.