  Despite the surging development and utilization of IoT devices, the security
of IoT devices is still in infancy. The security pitfalls of IoT devices have
made it easy for hackers to take over IoT devices and use them for malicious
activities like botnet attacks. With the rampant emergence of IoT devices,
botnet attacks are surging. The botnet attacks are not only catastrophic for
IoT device users but also for the rest of the world. Therefore, there is a
crucial need to identify and mitigate the possible threats in IoT devices
during the design phase. Threat modelling is a technique that is used to
identify the threats in the earlier stages of the system design activity. In
this paper, we propose a threat modelling approach to analyze and mitigate the
botnet attacks in an IoT smart home use case. The proposed methodology
identifies the development-level and application-level threats in smart home
use case using STRIDE and VAST threat modelling methods. Moreover, we
reticulate the identified threats with botnet attacks. Finally, we propose the
mitigation techniques for all identified threats including the botnet threats.
