The detection rule 'Cloud Instance Modified By Previously Unseen User' identifies activities where cloud instances, specifically AWS EC2 instances, are modified by users who have not previously made modifications to those instances. This is a crucial indicator of potentially unauthorized or suspicious activities that may arise from compromised accounts or malicious insiders. By leveraging the Change data model from AWS CloudTrail data, the rule isolates instances that were modified successfully and attributes these actions to users. The analytical process begins with querying the Change data model for successful modifications of EC2 instances, filtering by users not previously associated with these changes, and denoting the first time these users have made modifications. This can act as an early warning sign for potential unauthorized access or cloud infrastructure risks, emphasizing the need for swift response measures when such anomalies are detected.