Create an Amazon Simple Notification Service (Amazon SNS) topic. Subscribe the security team's email addresses to the SNS topic. Create a custom AWS Lambda function that will run the aws cloudformation validate-template AWS CLI command on all CloudFormation templates before the build stage in the CI/CD pipeline. Configure the CI/CD pipeline to publish a notification to the SNS topic if any issues are found.

Create an Amazon Simple Notification Service (Amazon SNS) topic. Subscribe the security team's email addresses to the SNS topic. Create custom rules in CloudFormation Guard for each resource configuration. In the CI/CD pipeline, before the build stage, configure a Docker image to run the cfn-guard command on the CloudFormation template. Configure the CI/CD pipeline to publish a notification to the SNS topic if any issues are found.

Create an Amazon Simple Notification Service (Amazon SNS) topic and an Amazon Simple Queue Service (Amazon SQS) queue. Subscribe the security team's email addresses to the SNS topic. Create an Amazon S3 bucket in the shared services AWS account. Include an event notification to publish to the SQS queue when new objects are added to the S3 bucket. Require the developers to put their CloudFormation templates in the S3 bucket. Launch EC2 instances that automatically scale based on the SQS queue depth. Configure the EC2 instances to use CloudFormation Guard to scan the templates and deploy the templates if there are no issues. Configure the CI/CD pipeline to publish a notification to the SNS topic if any issues are found.

Create a centralized CloudFormation stack set that includes a standard set of resources that the developers can deploy in each AWS account. Configure each CloudFormation template to meet the security requirements. For any new resources or configurations, update the CloudFormation template and send the template to the security team for review. When the review is completed, add the new CloudFormation stack to the repository for the developers to use.