CAN Bus Signal Inference for Unauthorized Message Detection
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Solution Overview
Problem
The Controller Area Network (CAN) bus in vehicles lacks message authentication, allowing unauthorized devices to mimic legitimate transmissions, posing security risks such as data theft and potentially life-threatening actions like inducing unsafe throttle or braking.
Innovation Solution
Implement an electronic device with an electronic processor and storage medium that performs CAN bus signal format inference and anomaly detection, extracting signals, detecting anomalies, and generating alerts, using proprietary and standard DBC files to identify and authenticate messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the CAN bus uses open architecture to allow ad hoc addition of new electronic components, then the adaptability and versatility of the system is improved, but the security and reliability of the network deteriorates as unauthorized devices can mimic legitimate transmissions
Solution Approach 1:
The patent introduces an intermediary authentication mechanism that verifies the legitimacy of messages on the CAN bus. This intermediary system checks message authenticity using secret keys and authentication codes, acting as a mediator between the open network architecture and security requirements, allowing new components to be added while preventing unauthorized transmissions
Solution Approach 2:
The patent implements preliminary authentication actions by pre-configuring secret keys and authentication parameters in ECUs before they connect to the CAN bus. This preliminary setup ensures that any device attempting to communicate on the network must first prove its legitimacy through cryptographic verification, preventing unauthorized devices from mimicking legitimate transmissions
2Reliability
If message authentication is implemented on the CAN bus to prevent unauthorized transmissions, then the security and reliability are improved, but the device complexity and processing overhead increase
Solution Approach 1:
The patent changes the parameter of authentication from complex cryptographic protocols to simplified authentication codes derived from pre-shared secret keys. This parameter change maintains security reliability while reducing device complexity by using lightweight authentication mechanisms suitable for resource-constrained ECU environments
Solution Approach 2:
The patent uses copying of authentication codes and secret keys across multiple ECUs in the network. Each ECU receives copies of authentication parameters during manufacturing or initialization, eliminating the need for complex real-time key exchange protocols and reducing processing overhead while maintaining security
3Productivity
If larger payload capacities are used in CAN-TP transmissions to send firmware updates, then the productivity of firmware updates is improved, but the risk of malicious code transmission increases
Solution Approach 1:
The patent introduces an intermediary authentication and verification mechanism for CAN-TP firmware updates. This intermediary system verifies the authenticity of large payload transmissions using authentication codes, acting as a mediator between the high-productivity CAN-TP protocol and security requirements, allowing efficient firmware updates while detecting and blocking malicious code
Solution Approach 2:
The patent implements feedback mechanisms where receiving ECUs verify authentication codes for incoming firmware update payloads and provide feedback on verification results. This feedback loop ensures that even large payload transmissions are securely validated, maintaining productivity while preventing malicious code execution through real-time verification
Data Source
AI summary
CAN bus signal format inference includes: extracting candidate signals from training CAN bus message traffic; defining one or more signals, each signal being a candidate signal that matches structural characteristics of a matching data type and each signal being assigned the matching data type; and generating an inferred CAN bus protocol with which the defined one or more signals conform. Signals are extracted from CAN bus message traffic using the inferred CAN bus protocol, an anomaly in an extracted signal is detected, and an alert is generated indicating the detected anomaly. In another aspect, a transport protocol (TP) signal is extracted and analyzed to determine a fraction of the TP signal that matches opcodes of a machine language instruction set, and an anomaly is detected based at least in part on the determined fraction exceeding an opcode anomaly threshold.