The 'Box New Login' detection rule is designed to identify user login activities to Box from new devices. When a user logs in from a device that hasn't been previously associated with their account, this rule triggers. It is focused on Initial Access via Valid Accounts, highlighting potential account access risks. The rule logs events categorized under Box.Event and particularly looks for the event type 'ADD_LOGIN_ACTIVITY_DEVICE' to distinguish legitimate logins from potentially malicious attempts. While the alert severity is classified as 'Info', indicating that the event is noteworthy but not necessarily indicative of an immediate threat, it requires investigation to confirm the legitimacy of the user’s access, as described in the runbook. The references provided guide users to further information on managing device access within Box.