The 'GCP Logging Sink Modified' rule is designed to monitor and detect modifications to Google Cloud Platform (GCP) log sinks, which are essential components for managing log data. This rule leverages GCP audit logs as a data source to trigger alerts on changes made to log sinks, thereby identifying potential malicious activities such as log exfiltration or attempts to avoid detection by adversaries. The rule is configured for an informational alert level, indicating that any modification should be reviewed but does not trigger an alert automatically. The response to detection involves validating the legitimacy of the modification, ensuring that it aligns with expected behaviors.