Our technological society has become more and more de-pendent on software that is used to automate everyday pro-cesses. This dependence increasingly exposes us to the se-curity threats that originate from malicious software (mal-ware) such as computer viruses and worms and softwarevulnerability exploits such as remote execution of code ordenial of service attacks. Moreover, this exposure is notlimited to computer systems but is spreading to common ap-pliances such as mobile phones, PDAs and consumer elec-tronics such as media centers, personal video recorders, etc.since a growing number of these products are made exten-sible and adaptable by means of embedded software.