This rule detects modifications to Amazon EC2 Route Tables through CloudTrail logs, specifically looking for the creation of a route (event name: CreateRoute). The detection is triggered when the CreateRoute API call is logged, indicating a new route was added to an existing route table. It monitors multiple attributes such as user identity, event time, source IP, and the specific route table ID that was modified. The severity of this alert is set to Info, implying it's not a critical alert but important for monitoring potential changes in network routing which could indicate exfiltration attempts over unintended paths.