Proposal and Application of Security/Safety Evaluation Method for Medical Device System that Includes IoT

A new risk analysis method for the Internet of Things (IoT) is required. IoT devices are exposed to both security and safety threats. Therefore, in the field of IoT, it is necessary to handle security and safety integrally, although these areas were treated as separate fields in the past. In the present paper, we propose a risk analysis method that can deal with both security and safety based on a safety analysis method called system-theoretic process analysis (STPA). In addition, we present a case in which the proposed method is applied to an insulin pump, which is a device for diabetic patients. In this case, using the proposed method, the occurrence of accidents due to security threats, which cannot be prevented by functional safety, could be identified. In addition, we showed a method of selecting countermeasures that can reduce the probability of the accident occurrence most among the limited budget.