A self-service terminal

A self-service terminal (10) comprising a plurality of components associated with a valuable media, such as a card reader (28) or cash dispenser (30). Each component includes or is associated with one or more sensors for detecting potentially fraudulent activity and a component agent (34) for generating a warning signal in the event that such activity is detected. Also provided is a higher level agent (38) that is operable to receive warning signals from the component agents (34), and use the received signals to identify potentially fraudulent activity. By providing a hierarchy of fraud detection agents (34,38), the likelihood of a fraud being successfully detected is improved.