It is very essential to add the 'Successful Login Notification' feature to Moodle. The user, once successfully login, will receive a notification by mail saying that he was successfully logged in to Moodle. 

The purpose of this feature, is to immediately inform the user if someone else managed to login with his credentials. That way the user can immediately react (i.e. inform the IT department of a potential impersonation) once receiving a notification by mail informing him that he logged in successfully.

We had an issue when a student managed to steal the teacher's credential. That way the student easily stole not only the upcoming exam but also all the bank of question