Summary Using the Smart Home as a use case, we examine the vulnerabilities in the system across the technologies used in its implementation. A typical smart home will contain a variety of sensors, actuators (e.g. for opening doors), communication links, storage devices, video cameras, network interfaces, and control units. Each of these physical components and subsystems must be secure in order for the overall system to be secure. Typical security analysis focuses on the defined interfaces of the system: network security via firewalls, communications encryption, and authentication at terminals. Unfortunately, many of these devices in the Internet of Things (IoT) space are susceptible to physical attacks via electromagnetic energy, or other sound/heat energy. Properly designed electromagnetic (EM) waveforms can access a range of vulnerabilities, providing unanticipated entry points into the system. In this chapter, we discuss a multi-modeling methodology for analyzing cyber-physical vulnerabilities, assessing the system across geometry, electronic, and behavioral domains. A home automation system is used as an example, showing a methodology for assessing vulnerabilities in hardware. The example exploits the use of EM energy injection. A multi-modeling of the system captures the geometric structure of the hardware with links to behavioral models. Low-energy EM pathways are discovered that may impact system behavior. Computation is minimized by applying analysis of EM effects only at behavior-critical inputs and outputs. The chapter also discusses a methodology for system-level impact analysis. The final conclusion is that susceptibility to physical layer presents many attack surfaces, due to a large number of heterogeneous IoT devices, mandating consideration of the physical dimensions to vulnerability analysis and risk mitigation.