The increasing rate at which IoT technologies are being developed has enabled smarter and innovative solutions in the sectors of health, energy, transportation, etc. Unfortunately, some inherent characteristics of these technologies are compromised to attack. Naturally, risk analysis emerges, as it is one of many steps to provide a reliable security strategy. However, the methodologies of any risk analysis must first adapt to the dynamics of the IoT system. This article seeks to shed light on whatever factors are part of an IoT system and thus contribute to security risks, IoT device vulnerabilities, susceptibility due to the application domain, attack surfaces, and interdependence as a product of the interconnection between IoT devices. Consequently, the importance of these factors in any risk evaluation is highlighted, especially the interdependence generated by IoT systems, which can cause the generation of an uncontrollable cascade of effects that can occur under certain conditions of any systematic risk event.