  Cardiac Implantable Electronic Devices (CIED) are fast becoming a fundamental
tool of advanced medical technology and a key instrument in saving lives.
Despite their importance, previous studies have shown that CIED are not
completely secure against cyber attacks and especially those who are exploiting
their Radio Frequency (RF) communication interfaces. Furthermore, the telemetry
capabilities and IP connectivity of the external devices interacting with the
CIED are creating other entry points that may be used by attackers. In this
paper, we carry out a realistic risk analysis of such attacks. This analysis is
composed of three parts. First, an actor-based analysis to determine the impact
of the attacks. Second, a scenario-based analysis to determine the probability
of occurrence of each threat. Finally, a combined analysis to determine which
attack outcomes (i.e. attack goals) are riskiest and to identify the
vulnerabilities that constitute the highest overall risk exposure. The
conducted study showed that the vulnerabilities associated with the RF
interface of CIED represent an acceptable risk. In contrast, the network and
internet connectivity of external devices represent an important potential
risk. The previously described findings suggest that the highest risk is
associated with external systems and not the CIED itself.
