A company manages AWS accounts for application teams in AWS Control Tower.

Create a CloudFormation custom resource that invokes an AWS Lambda function. Configure the Lambda function to conditionally enable GuardDuty if GuardDuty is not already enabled in the accounts.

Use the Conditions section of the CloudFormation template to enable GuardDuty in accounts where GuardDuty is not already enabled.

Use the CloudFormation Fn. GetAtt intrinsic function to check whether GuardDuty is already enabled If GuardDuty is not already enabled use the Resources section of the CloudFormation template to enable GuardDuty.

Manually discover the list of AWS account IDs where GuardDuty is not enabled Use the CloudFormation Fn: ImportValue intrinsic function to import the list of account IDs into the CloudFormation template to skip deployment for the listed AWS accounts.