Techniques of authenticating a new user involve classifying a new user as a member of a group based on the new user's current activity. Along these lines, when a new user enrolls in an authentication system, the authentication system places the new user in a group of new users that have not made any requests and are assumed to be high risks of making fraudulent requests. Once the new user makes a request to access a resource, the authentication system classifies the new user as a member of another group according to authentication factors describing activities surrounding the request.