Today, AWS CloudFormation StackSets launches a new API ListStackInstanceResourceDrifts, and adds a new filter in ListStackInstances to improve visibility to resource and stack instance drift information. A resource or stack instance is considered drifted when it’s actual configuration differs from its expected configuration. You can now use ListStackInstanceResourceDrifts to list and filter resources in a stack instance according to drift status. Similarly, you can use the drift status filter in ListStackInstances to check for stack instance drift in a stack set. With this launch, you can access these aggregated drift information through your management or delegated administrator AWS account.
Source:: Amazon AWS