# Threat Analysis for Smart Homes +
## 4 Threat Analysis
### The Case of the Smart Home Ecosystem  
The smart home ecosystem includes multiple assets, depending on the viewpoint. In this work, we focus on the physical and communication viewpoints, thus we aim at identifying information and physical assets. These are depicted in Table 1.  
Based on the identified assets and various device and back-end service communication scenarios, we then developed six distinct Smart Home scenarios, described by the corresponding DFDs, representing six topologies of varying complexity, so as to approach the dynamic nature of the target environment [8]. These are described below and the corresponding DFDs are shown in Figure 1:  
_Scenario 1--IP camera and IoT gateway:_ The first scenario represents the connection between an IP camera and a gateway, as depicted in Figure 1a. The ZigBee protocol is used for communication and our analysis focuses on threats which could harm either the physical assets or information transmitted between the devices. We assume that the IP camera is connected directly to the gateway. \begin{table}
\begin{tabular}{c c} \hline \hline
**Information Assets** & **Physical Assets** \\ \hline User credentials & IoT smart devices \\ Information collected by smart devices & IoT hubs \\ Smart home status information & IoT gateways \\ Information about the installed assets & Sensors/Actuators \\ Log information & Cloud server \\ Video, Picture, Voice Information & \\ Location tracking information & \\ Personal information (e.g., health data) & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Identified assets [8]. _Scenario 2--Unidirectional communication between an IP camera and the cloud:_ This topology represents a connection between an IP camera and a cloud server through two gateways. The communication is established using three different protocols, as can be seen in Figure 1b. In this scenario, the IP camera sends only a request to the database. The former is connected directly to the gateway through the ZigBee protocol and the latter is a simple database which uses MySQL 2016. _Scenario 3--Bidirectional communication between an IP camera and the cloud:_ The third topology is similar to the second, but now the IoT device communicates with the cloud bidirectionally. The used communication protocols are depicted in Figure 1c. _Scenario 4--Smartphone controlled IP camera:_ A more complex topology is represented in the next scenario depicted in Figure 1d. This topology describes the communication between a smartphone-controlled IP camera and the cloud. The IoT device (smartphone) sends requests to the cloud API in order to control the IP camera through cellular communication. _Scenario 5--Smartphone communication with the cloud:_ The next topology represents the communication between the smartphone and the cloud as illustrated in Figure 1e. In this topology, we aim to identify potential threats that could provoke damage to the control requests. _Scenario 6--Links among smart devices:_ The last topology targets only smart devices (IP camera, alarm system and smartphone) and aims to identify potential threats which derive from parallel links among these devices. In particular, the IP camera is able to communicate using 4G and the ZigBee protocol. The topology in Figure 1f depicts the interaction of an IP camera with a smartphone and with an alarm system. By applying the STRIDE method to these scenarios, in [8], we identified in detail the relevant threats. The number of threats identified in each of the six scenarios is depicted in Table 2. The following conclusions on how the dynamic nature of a smart home environment affects the identified threats can be drawn [8]:  
* As the complexity of the topology increases, more security threats are identified. In the last two scenarios, fewer threats have been identified since the analysis focused on the communication between the smartphone and the cloud and on the identification of threats which derive from parallel links among specific devices. * More complex topologies inherit the threats that the simpler ones face.