The GCP Firewall Rule Created detection rule is designed to monitor the creation of firewall rules within Google Cloud Platform (GCP). This rule leverages GCP Audit Logs to detect any insert operations related to firewall rules and identifies the authentication details of the user making the change. When a firewall rule is created, this could potentially expose sensitive resources to the internet, making it crucial to verify whether the creation of such firewall rules was intended. The rule is considered low severity, indicating that although it warrants monitoring, it might not pose an immediate threat unless accompanied by a lack of authorization or unexpected rules being created. The rule implements several tests to validate its detection capability, ensuring that alerts are generated only for appropriate firewall creation methods, preventing false positives from other firewall-related operations such as updates.