Information Security Risk Analysis Method Research For Fully Automatic Operation System

As the core of the safety and efficient operation of rail transit,the train control system has always faced the threat of information security.With the further popularization and development of network and automation,Fully Automatic Operation(FAO),which is based on technologies of modern computer,communication and control to realize the full automatic operation,has become the trend of the development in the field of urban rail transit in China because of its high efficient,low cost operation and other characteristics.Nevertheless,due to the automation of equipment and the networking of signal systems and control systems,it is suffering tremendous information security threats and challenges.Therefore,combing the characteristics of full automatic operation and formulating the research method that applies to the system have become priority of current research work.This thesis analyze the increased information security threats of fully automatic operation system compared to the traditional system,explore its basic components and information security situation and the information flow in the operation scene and deeply grasp the information security characteristics of the system.In this thesis,the information security risk analysis method which is suitable for fully automatic operation system is studied from the theory of information security risk analysis and the information security characteristics of fully automatic operation system.The traditional risk analysis theory is optimized to make it more suitable for the characteristics of the analysis object of the urban rail industry.Based on it,Risk Analysis Method Based on Attack Tree and CVSS(RAM-AT&C)is proposed.The focus and innovation of the analysis method are as follows:(1)This thesis purposes the analytical theory that the information security risk of fully automatic operation system depends on the risk consequences of its various subsystems.The information security risk assessment of the entire system relies on the superposition and quantification of the risk analysis results of all subsystems.(2)The risk element identification step of the analysis object is set as the basic link in the risk analysis method,including strategic identification and service identification,asset identification and assignment,threat identification,and vulnerability identification.The accurate identification of these risk factors is directly related to the establishment of the correct construction of attack tree and the establishment of the traceability system.(3)The traditional attack tree model is optimized,the traceability of risk factors is combined with the path of attack tree,and the complete attack process is traced and restored in the form of attack sequence.(4)Quantitative analysis is added on the basis of regularity analysis.By means of the improved CVSS 3.0 scoring method and the calculation formula of the risk value defined according to the characteristics of fully automatic operation system,the results are analyzed according to the specific risk probability,the risk value and the vulnerability availability value,and the protective measures with certain priority levels are made.In order to verify the whole method,an important part of fully automatic operation system,Zone Controller,is used as an example of the analysis object,and the risk analysis is performed in full according to the analysis method proposed in this thesis.The analysis shows that the most influential functions include train safety location calculation,train mobility authorization calculation,zone controller switching,etc.And the conclusion that the attack on zone controller can only affect the operation efficiency is made,and the protection suggestion is put forward accordingly.Not only the feasibility and credibility of the framework is verified,but also important basis and analysis results,which could set targeted analysis of information security protection measures and realize state analysis at any time,are supported by quantitative analysis.Evaluators could formulate information security requirements and protection measures based on the analysis results in combination with the actual project,improve the system settings of fully automatic operation system and make the operation of the train more stable and safe.