As technology improves at an astounding rate, cities have to improve their services in terms of safety, healthcare, transportation, and the overall welfare of their residents. Internet of Things (IoT) play a major role in the infrastructure of a smart city by gathering and processing data from distributed sensors to implement smart services, such as traffic control, environment monitoring, and waste management. However, the most challenging part is securing data from various attacks while maintaining low-complexity techniques and algorithms. Considering security concerns to the deployment of IoT as the main source of data collection and transmission, attacks are classified to identify a suitable scheme of defending against them. This paper provides a two-fold contribution to analyze security and privacy in the context of smart cities for healthcare applications. Thus, on one hand an overview of different IoT applications and their cyber vulnerabilities are presented. On the other hand, a comprehensive evaluation of possible approaches to mitigate the problem of cyber attacks is described. © 2018 IEEE.