## 4 Proposed Test Simulation
### Virtual Machine-Linked Node Test  
In this section, to verify the proposed simulation test environment, we tested whether it is possible to send/receive data between the virtual machine and simulation nodes, create vehicle nodes, perform driving, and create events without using the scenario editor in the simulation. The implementation target regions for this test were targeted at specific regions in Incheon and Seoul, which are V2X test beds in Korea. Figures 9 and 10 show the Incheon area and Figure 11 shows the Seoul area. In conventional simulations, the user must specify vehicle nodes' routes, speeds, and events using the scenario editor tool, as shown in Figure 9. When the created scenario is executed in the simulation, each node sends and receives V2X messages while driving according to the scenario created with the editor tool. Simulations using the scenario editor have a significant disadvantage in using them for security evaluation: the simulations can only be performed according to the scenarios defined in the editor tool. This makes it difficult to simulate situations for changes due to the external input of the V2X message values, such as GPS and speed, or the appearance of a vehicle that did not exist. In the simulation environment proposed in this paper, it is easy to create unexpected situations that are difficult to create with the scenario editor. Since vehicles' sudden appearance and events can be implemented in the simulation, various situations required for security testing can be created. Figure 8: Environment composed of laboratory laptop and CANoe. Figure 9: The simulation editor of the simulation equipment used in this paper. Using the scenario editor, the user can specify vehicle nodes’ routes, speeds, and events. When the simulation is executed, each vehicle node drives according to the scenario specified by the user. The simulation node receives data from the virtual machine, generates a V2X message according to the standard message specifications, and sends the data to the simulation network. As a result of sending a V2X message from the virtual machine to a simulation node, we found that the vehicle node can be driven without using the simulation editor, as shown in Figure 10. Furthermore, a vehicle event could be generated at a specific location using the BSM Part II data, which contains 13 types of vehicle event information. The simulation node linked to the virtual machine is implemented to collect data from a specific node so that the BSM generated in the network can be collected. Then, a simple GPS spoofing attack scenario was created. Using this scenario, we collected data for the normal driving situation and data for the GPS spoofing attack situation. Through this, we checked whether the GPS spoofing attack message, fed through the virtual machine, affected the simulation network as intended. As an attack scenario, we implemented a simple GPS spoofing scenario in which the GPS values in the BSM are sent with latitude and longitude values that are not related to the driving route using the same address as the normal driving target vehicle. Through the graph, we analyzed how the latitude and longitude values change over time in the collected GPS spoofing scenario data. There were two GPS spoofing scenarios: performing a spoofing attack from a specific point in time to the end and performing a spoofing attack intermittently. As a result of the analysis, we found that the third vehicle node perceived that the location information of the target vehicle changed continuously as shown in Figure 11.  
Figure 11: This figure shows a GPS spoofing scenario in which the GPS values are changed using the same address and ID in a vehicle node driving usually. The third vehicle perceives that the GPS information of the vehicle, with the pertinent ID, changes continuously, as shown in the figure. Figure 10: This figure shows driving by sending V2X data to a simulation node linked to the virtual machine and generating a vehicle event (hard braking) without using the scenario editor.