Watching systems in action: security at the periphery

Computer security is maintained in many ways. New systems are developed with an eye towards protecting against known techniques for bypassing system controls. New methods of fraud, especially in point of sale systems, appear in spite of these protections. Consequently, there is a continuing need to examine how systems are used in practice and to implement new controls to prevent the incidence and recurrence of fraud. This paper cites examples of new frauds, suggests general techniques for protecting against the original appearance and recurrence of such frauds, and proposes that the maintenance of computer systems include continuing attention to these controls.