Patching an Engine Control Module to Enhance Security

Abstract

The architecture of Controller Area Network (CAN)-based protocols offers straightforward, centralized, and cost-efficient methods for various Electronic Control Units (ECUs) to communicate via the CAN bus. However, the CAN protocol was not designed with security as a priority. The CAN bus used in vehicles lacks built-in security features, (i.e., messages are broadcast without authentication or encryption). This makes CAN vulnerable to eavesdropping, spoofing, and replay attacks. Any compromised node can inject false messages (e.g., impersonating the brakes or engine controller) with no cryptographic checks to stop it. The protocol’s primary integrity safeguard, a Cyclic Redundancy Check (CRC), was designed solely for detecting transmission errors and is easily manipulated, offering no real protection against malicious adversaries. Implementing cryptography on CAN is challenging due to CAN’s most popular limited 8-byte data payload, real-time latency requirements, and the need for compatibility with millions of existing CAN devices. To address this issue, this study focuses on developing a Cryptographic Message Authentication Code (CMAC) Intrusion Detection System (IDS) implementation for CAN bus communication using existing ECUs.