Design And Implementation Of CAN Bus Protocol Reverse Technology Based On Fuzzing

With the rapid development of the connected vehicles,the safety situation of vehicles is becoming more and more serious,and the safety of vehicles has been paid more and more attention.Since the attacks on vehicles are ultimately realized by invading the Control Area Network(CAN)bus,strengthening the security protection of CAN bus is one of the most important ways to strengthen the security of the vehicle.Knowing the details of CAN bus protocol can make the security analyst better protect the CAN bus.However,the car manufacturers are not willing to disclose the protocol at present,which makes the research and protection work of security analyst difficult.Since this situation can not be changed in a short time,the security community has a need to reverse the CAN bus protocol.The development of the reverse engineering of CAN bus protocol is grad-ual.At first,it was simply to associate CAN bus data with ECU,and then it developed to reverse the CAN protocol syntax,and then to reverse the seman-tics.This paper proposes a complete semantic reverse scheme of CAN bus protocol.In this paper,the semantic reverse scheme of CAN bus protocol is divided into two stages:one is recognition syntax:extracting and classifying the signals in CAN data;the other is reverse semantics:designing corresponding schemes for different signals to reverse their functional meanings.The reason why it is designed into these two stages is that accurate syntactic recognition can bring great help to semantic reverse.The following introduces the work and contribution of the two stages of this paper.In the recognition syntax stage,this paper improves the READ algorithm.Read algorithm is an excellent syntax reverse scheme of CAN bus protocol in academia.Read algorithm divides CAN signal into physical quantity,counter and check value.In this paper,the characteristics of CAN signal are further studied,and the signal is divided more carefully.Firstly,signals are divided into three categories:single-valued signals,multi-valued signals and full-valued signals.Then,the multi-valued signals are further subdivided into control instructions and discrete physical quantity signals,and the full-valued signals are further subdivided into continuous physical quantity signals,counter signals and check value signals.In the reverse semantic stage,this paper designs corresponding reverse schemes for different signals.The schemes of single-valued signals,multi-valued signals(control instructions,discrete physical quantity signals)and full-valued signals(counter signals,check value signals,continuous physi-cal quantity signals)are independent.The reverse of control instructions in multi-valued signals is based on the strategy Fuzzing and bit ADD operation algorithm proposed in this paper;The reverse of discrete physical quantities signals in multi-valued signals is based on the numerical law comparison al-gorithm proposed in this paper;The reverse of continuous physical quantities signals in full-valued signals is realized by using the idea of data fitting.