A novel method of dealing with the problem of phishing, pharming, key-logging and man-in-the-middle attacks on internet-based applications which require the submission of valid login credentials, by permitting a user to control access to an internet-based application (3) (such as an internet banking website) by the simple transmission of a command via the internet to allow access to the internet-based application (3) whenever the user wishes to access the application, and by transmitting a command via the internet to deny access to the internet-based application at all other times, to prevent unauthorized access by any unscrupulous parties.