Research On Characteristics Of Covert Attack Method For Pressurizer In Nuclear Power Plant

In nuclear power plant,pressure control system of pressurizer is a distributed industrial control system composed of pressurizer,controller,pressure sensor and other equipment,which is connected through communication network.It has the advantages of fast response and convenient use.With the opening and interconnection of information network technology,relevant technologies gradually penetrate into the industrial communication system,which not only improves the intelligence of industrial control system,but also gradually increases the number of attack vulnerabilities at all levels,making it vulnerable to different types of attack threats.Therefore,from the perspective of control security,this paper studies the design,implementation and attack characteristics of replay attack and covert attack in the pressure control system of pressurizer.The main research work is as follows:(1)The information security problems faced by the pressure control system of pressurizer are analyzed.This paper analyzes the attack vulnerabilities in the industrial control system from the network layer and physical layer,and cl assifies the attack types in the industrial control system.Due to the high concealment and strong destruction of replay attack and covert attack,it has become the focus of industrial security research.(2)A method of pressurizer modeling based on LSSVM is proposed.Aiming at the problems of high delay and high control accuracy in the pressure control system of pressurizer,a modeling method based on SVR and LSSVM is proposed.Through experimental comparison,it is found that LSSVM can not only overcome t he shortcomings of SVR,such as many operating parameters,complex calculation and slow running speed,but also maintain high identification accuracy and better fit the input and output behavior of pressurizer.(3)The attack models of replay attack and feedback covert attack based on LSSVM are designed.Firstly,the attack space of industrial control system and the general threat model of covert attack are introduced.On this basis,the attack principles of replay attack and covert attack are introduced.Then,according to the pressure control structure of pressurizer,the attack models of replay attack and feedback covert attack based on LSSVM are designed,and the anomaly detector based on improved CUSUM algorithm is designed for attack detection.(4)The characteristics of covert attack are analyzed.By setting up attack simulation experiments under different conditions,the attack characteristics of replay attack and covert attack based on LSSVM are analyzed.Through the experimental test,it is found that the replay attack is suitable to be implemented in the steady-state stage of the system and is not disturbed by the conditions such as noise and sample integrity,but it is not suitable to be implemented in the dynamic stage of the system and the change stage of the system setting value,which will interfere with its attack stability;The feedback concealment attack based on LSSVM has stronger adaptability and robustness.It has good concealment and aggression under variable working conditions such as system steady-state,dynamic and set value change.It is not limited by conditions such as noise or model type,but its attack concealment will be affected by sample integrity.