A controller area network (CAN) bus connects all electronic control units (ECUs) in contemporary automobiles, allowing them to communicate and carry out tasks. Modern automobiles’ increased connectivity and complexity have raised serious questions about their security, though. Because they employ a broadcast communication technique and lack authentication, CANs are especially vulnerable to attacks using message injection. The CAN in automobiles is an extremely useful tool for both attack and defense. The purpose of the bus-off attack is to put an ECU in the bus-off state and use the fault confinement of the CAN to prevent it from using the bus. The chapter presents a simulation framework for CAN utilizing the MCP2515 CAN controller. To simulate real-world situations, the program introduces error simulation. Error states are divided into three categories: ACTIVE, PASSIVE, and BUS-OFF. Error state transitions are based on the error counter, which is used to track and react to errors. Furthermore, the program includes error recovery mechanisms that demonstrate how to reset the MCP2515 and get it back to normal operation if it encounters a BUS-OFF state.