Cross‐layer security design for encrypted CPS based on modified security signalling game

Recent years have witnessed increasing cyber and physical attacks against encrypted cyber‐physical system (CPS) and the ensuing catastrophic consequences. A modified security signaling game (MSSG) model is proposed for capturing attack‐defense interactions and analyzing the cross‐layer security of encrypted CPS. Cyber real‐time performance and physical control performance are both considered in cross‐layer utility function. Theorems concerning the existence of pure‐strategy and mixed‐strategy perfect Bayesian Nash equilibrium (PBNE) are provided, based on which a cross‐layer security design algorithm is proposed for defender's optimal strategy against potential attacks. A numerical case is studied with the effectiveness of our method being proved.     

基于贝叶斯序贯博弈模型的智能电网信息物理安全分析

智能电网是利用信息技术优化从供应者到消费者的电力传输和配电网络.作为一种信息物理系统（Cyber-physical system,CPS）,智能电网由物理设备和负责数据计算与通信的网络组成.智能电网的诸多安全问题会出现在通信网络和物理设备这两个层面,例如注入坏数据和收集客户隐私信息的网络攻击,攻击电网物理设备的物理攻击等.本文主要研究了智能电网的系统管理员（防护者）如何确定攻击者类型,从而选择最优防护策略的问题.提出了一种贝叶斯序贯博弈模型以确定攻击者的类型,根据序贯博弈树得到博弈双方的均衡策略.首先,对类型不确定的攻击者和防护者构建静态贝叶斯博弈模型,通过海萨尼转换将不完全信息博弈转换成完全信息博弈,得到贝叶斯纳什均衡解,进而确定攻击者的类型.其次,考虑攻击者和防护者之间的序贯博弈模型,它能够有效地帮助防护者进行决策分析.通过逆向归纳法分别对两种类型的攻击者和防护者之间的博弈树进行分析,得到博弈树的均衡路径,进而得到攻击者的最优攻击策略和防护者的最优防护策略.分析表明,贝叶斯序贯博弈模型能够使防护者确定攻击者的类型,并且选择最优防护策略,从而为涉及智能电网信息安全的相关研究提供参考.     

Resilient control of cyber-physical systems against intelligent attacker: a hierarchal stackelberg game approach

This paper is concerned with the resilient control under denial-of-service attack launched by the intelligent attacker. The resilient control system is modelled as a multi-stage hierarchical game with a corresponding hierarchy of decisions made at cyber and physical layer, respectively. Specifically, the interaction in the cyber layer between different security agents is modelled as a static infinite Stackelberg game, while in the underlying physical layer the full-information H^∞ minimax control with package drops is modelled as a different Stackelberg game. Both games are solved sequentially, which is consistent with the actual situations. Finally, the proposed method is applied to the load frequency control of the power system, which demonstrates its effectiveness.     

A Stochastic Game Model for Evaluating the Impacts of Security Attacks Against Cyber-Physical Systems

A quantitative security evaluation in the domain of cyber-physical systems (CPS), which operate under intentional disturbances, is an important open problem. In this paper, we propose a stochastic game model for quantifying the security of CPS. The proposed model divides the security modeling process of these systems into two phases: (1) intrusion process modeling and (2) disruption process modeling. In each phase, the game theory paradigm predicts the behaviors of the attackers and the system. By viewing the security states of the system as the elements of a stochastic game, Nash equilibriums and best-response strategies for the players are computed. After parameterization, the proposed model is analytically solved to compute some quantitative security measures of CPS. Furthermore, the impact of some attack factors and defensive countermeasures on the system availability and mean time-to-shutdown is investigated. Finally, the proposed model is applied to a boiling water power plant as an illustrative example.     

DoS干扰攻击下的信息物理系统状态反馈稳定

基于网络的工业控制系统作为信息物理系统(CPSs)的一种重要应用正迅猛发展.然而,近年来针对工业控制系统的恶意网络攻击引起了人们对CPS安全问题的广泛关注.拒绝服务(DoS)干扰攻击作为CPS中最容易发生的攻击方式得到了深入研究.对此,提出一种能量受限的、周期的DoS干扰攻击模型,攻击的目的是增大无线信道发生数据包随机丢包的概率.基于一类CPS简化模型,考虑CPS中传感器与控制器(S-C)之间无线信道同时存在DoS干扰攻击和固有随机数据包丢失的情况,采用状态反馈,基于随机Lyapunov函数和线性矩阵不等式方法得到可以保证系统稳定的充分条件,并利用系统稳定的充分条件和锥补线性化算法设计控制器.最后,通过两个数值仿真例子验证所提出控制策略的有效性.     

基于Stackelberg安全博弈的动态防御策略选取方法

网络攻防对抗的本质是攻防双方非对等主体之间的博弈过程。针对现有网络防御策略研究中攻防博弈双方主体地位对等的先验假设缺陷,将博弈论非对等局中人思想引入网络防御策略生成模型构建过程,提出一种基于Stackelberg安全博弈的动态防御策略生成方法,通过建立网络模型,利用Stackelberg安全博弈强均衡策略算法生成网络的最优防御策略,既充分考虑攻防行为中双方关系彼此影响,又能确保防御策略生成的准确性。实验结果表明所提模型和方法的可行性和有效性。所提模型和方法能够加强系统的安全性。     

Dependency-based security risk assessment for cyber-physical systems

A cyber-physical attack is a security breach in cyber space that impacts on the physical environment. The number and diversity of such attacks against Cyber-Physical Systems (CPSs) are increasing at impressive rates. In times of Industry 4.0 and Cyber-Physical Systems, providing security against cyber-physical attacks is a serious challenge which calls for cybersecurity risk assessment methods capable of investigating the tight interactions and interdependencies between the cyber and the physical components in such systems. However, existing risk assessment methods do not consider this specific characteristic of CPSs. In this paper, we propose a dependency-based, domain-agnostic cybersecurity risk assessment method that leverages a model of the CPS under study that captures dependencies among the system components. The proposed method identifies possible attack paths against critical components of a CPS by taking an attacker’s viewpoint and prioritizes these paths according to their risk to materialize, thus allowing the defenders to define efficient security controls. We illustrate the workings of the proposed method by applying it to a case study of a CPS in the energy domain, and we highlight the advantages that the proposed method offers when used to assess cybersecurity risks in CPSs.

     

基于多跟随者Stackelberg博弈的流速控制算法

由于现实网络中,端系统的角色往往并不平等,存在某些端系统制定整个网络的流速控制策略,其他端系统只能跟随这些策略,不能简单地使用非合作博弈理论研究Internet中非合作端系统的贪婪行为。该文在讨论了一次博弈模型和流速控制博弈均衡的解析解的基础上,对多跟随者Stackelberg博弈模型的流速与拥塞控制行为进行了深入研究。提出了多跟随者Stackelberg博弈流速控制模型,论证了Stackelberg均衡的存在性,并推导出在Stackelberg均衡点上领导者和多跟随者流速率的解析解。最后,文章设计了一种基于多跟随者Stackelberg博弈的流速控制算法(FCSM),并讨论了FCSM算法执行的过程。     

Game and Dynamic Communication Path-Based Pricing Strategies for Microgrids Under Communication Interruption

Nowadays,the microgrid cluster is an important application scenario for energy trading.In trading,one of the most important research directions is the issue of pricing.To determine reasonable pricing for the microgrid cluster,data communication is used to create the cyber-physical system(CPS),which can improve the observability of microgrids.Then,the following works are carried out in the CPS.In the physical layer:1) Regarding trading between microgrids and the load,based on the generalized game...     

Deep Learning Based Attack Detection for Cyber-Physical System Cybersecurity: A Survey

With the booming of cyber attacks and cyber criminals against cyber-physical systems(CPSs),detecting these attacks remains challenging.It might be the worst of times,but it might be the best of times because of opportunities brought by machine learning(ML),in particular deep learning(DL).In general,DL delivers superior performance to ML because of its layered setting and its effective algorithm for extract useful information from training data.DL models are adopted quickly to cyber attacks against CPS systems.In this survey,a holistic view of recently proposed DL solutions is provided to cyber attack detection in the CPS context.A six-step DL driven methodology is provided to summarize and analyze the surveyed literature for applying DL methods to detect cyber attacks against CPS systems.The methodology includes CPS scenario analysis,cyber attack identification,ML problem formulation,DL model customization,data acquisition for training,and performance evaluation.The reviewed works indicate great potential to detect cyber attacks against CPS through DL modules.Moreover,excellent performance is achieved partly because of several highquality datasets that are readily available for public use.Furthermore,challenges,opportunities,and research trends are pointed out for future research.     

基于Stackbelberg博弈的认知无线网络速率控制模型

提出了基于Stackelberg博弈的认知无线单跳网络流量速率控制模型。应用反向归纳法对提出的流量速率Stackelberg博弈模型纳什均衡进行了分析,证明了提出的模型纳什均衡存在性及唯一性,并给出了Stackelberg博弈模型纳什均衡解的具体形式。仿真验证了提出的模型正确性,仿真结果表明在模型的纳什均衡处网络总体效用是最优的,且网络效用最大时认知结点可获得最优数据传输速率。     

基于斯塔克尔伯格博弈的在线社交网络扭曲信息干预算法

在新冠肺炎疫情期间,社交媒体以前所未有的速度向全世界传播消息.然而,扭曲信息隐藏在海量社交数据中,对国家安全、社会稳定提出了前所未有的挑战.目前的干预措施大多是建立在对关键节点和关键链路进行控制的基础之上,即删帖和封号,往往效果不佳且容易产生副作用.基于扭曲信息的定义和分析,打破传统思维的限定,在信息蔓延过程中通过发布...     

协作通信中基于斯塔科尔伯格博弈的物理层安全分析

物理层安全不是利用传统的密钥加密,而是利用信道的传输特性使得合法的通信双方实现安全传输的方法。无线协作通信中节点行为对物理层安全的影响是至关重要的。本文应用斯塔科尔伯格博弈模型研究节点之间的利益,在中继自私的协作放大转发网络中,得到网络中节点之间的效用平衡的最优解存在条件,并提出一种分布式算法,找到网络平衡下的最优安全性能解。     

基于博弈论的信息物理融合系统安全控制

对于远程复杂的操控系统,信息物理融合系统（Cyber-physical system,CPS）主要依靠无线网络实现从传感器到控制器,从控制器到执行器间的信息传输,由于其依靠网络传输数据的特性使其控制系统极易遭到安全威胁.本文从物理系统入手,意图保护CPS系统中物理实体的正常运行不受由于恶意攻击造成网络空间入侵带来的干扰.以受到数据包时序攻击的信息物理融合系统为研究对象,将其安全性研究抽象为一个博弈过程,基于非合作博弈的两人零和博弈模型,设计了可变延迟情况下鲁棒输出反馈的极大极小控制器.并且采用参数化的软约束二次型目标函数,在控制器设计时引入干扰衰减因子γ,通过对γ的取值使得二次型目标函数取极小值,从而保证了最差情况下的稳定控制,在满足γ的约束条件下,本文通过粒子群搜索算法得出γ的值.另外,本文还对所设计的极大极小控制器,与线性二次型高斯（Linear quadratic Gaussian,LQG）控制对比分析,用双水箱系统进行了仿真验证,发现在受攻击情况下本文所设计的控制器最终能够实现稳定控制,而LQG却不能.     

基于Stackelberg攻防博弈的网络系统安全控制机制优化研究

企业级网络中存在的漏洞日益增多,给公司网络系统安全控制机制的优化选择带来了巨大挑战。本文通过对企业网络中漏洞之间的复杂依赖关系进行建模,构建了漏洞依赖图,并在此基础上建立了Stackelberg攻防博弈模型。同时考虑到传统求解方法无法求解实际的问题规模,引入双模块算法。实验结果表明,本文提出的模型和方法是可行的、高效的。     

位置约束的访问控制模型及验证方法

随着物联网和信息物理融合系统等新一代信息技术的发展,位置约束的访问控制系统的安全性需求不仅体现在虚拟的信息空间,还体现在现实的物理空间.如何在这种新需求下制定位置约束的访问控制模型与验证方法成为保证访问控制系统安全的关键所在.首先提出位置约束访问控制模型,包括LCRBAC模型和EM模型,实现对信息空间和物理空间的静态结构以及两空间中实体动态行为的刻画;其次利用偶图和偶图反应系统建模位置约束访问控制模型,生成访问控制策略标注转移边的标号变迁系统;然后根据标号变迁系统验证结果,提出针对死锁状态、违反状态和不可达状态的策略修改方案;最后通过银行访问控制系统实例分析说明所提方法能够对信息空间和物理空间以及两空间交互行为的访问控制策略进行建模和验证.     

An overlapping generations stochastic differential game

The paper presents a noncooperative stochastic differential game played by an infinite number of overlapping generations of players. The number and types of players in future generations are uncertain and the state dynamics are given by a stochastic differential equation. A Markovian Nash equilibrium is characterized by a verification theorem of the Hamilton-Jacobi-Bellman type. A resource extraction game is offered as an illustration.     

Multi-cyber framework for availability enhancement of cyber physical systems

With the rapid growth of wireless communication, the deployment of cyber-physical system (CPS) is increasing day by day. As a cyber physical system involves a tight coupling between the physical and computational components, it is critical to ensure that the system, apart from being secure, is available for both the cyber and physical processes. Traditional methods have generally been employed to defend an infrastructure system against physical threats. However, this does not guarantee that the availability of the system will always be high. In this paper, we propose a multi-cyber (computational unit) framework to improve the availability of CPS based on Markov model. We evaluate the effectiveness of our proposed framework in terms of availability, downtime, downtime cost and reliability of the CPS framework.     

基于Petri网的CPS系统安全量化分析模型

随着信息物理融合系统（CPS）的广泛应用,安全性已成为其研究的核心问题。由于CPS离散计算过程和连续物理世界交织的特性,传统的安全分析方式不能直接适用。通过将博弈理论和Petri网建模方法进行结合,提出一种GHPN方法对CPS系统建立量化的安全分析模型,该模型既能适用CPS离散连续混合结构的模型刻画,又可合理模拟系统攻防双方行为,基于最终生成的模型从系统可靠性、脆弱性、风险后果等方面进行安全分析。通过对飞机空中避撞系统的实例研究,表明该模型和分析方法的有效性。     

时滞和扩散驱动下信息物理融合系统恶意病毒传播动力学

本文提出了信息物理融合系统(CPS)中具有反应扩散效应的时滞恶意病毒传播模型, 研究了恶意病毒传播 的空间格局动态演化机制, 为恶意病毒在信息物理融合系统中预测和控制提供了战略指导. 给出了模型的基本再 生产数, 并分析了空间中无病毒平衡点和地方病毒平衡点的存在性. 在无时滞条件下建立了扩散引发的图灵不稳 定条件; 在有时滞条件下得到了时滞依赖的稳定性条件和Hopf分岔判据. 最后, 通过数值仿真验证了理论分析的正 确性.