列控系统信息安全风险主动防御研究

发布时间：2018-08-02 19:24

【摘要】：随着轨道交通列车运行控制系统的信息安全风险日益加剧,考虑到系统的特殊性和复杂性,一般工控系统的信息安全解决方案并不能很好地应用于列控系统。目前,国内外针对列控系统信息安全防御技术的研究很少且不深入,没有充分考虑列控系统数据驱动的特点,防御方面也没有结合“安全冗余结构”及“故障—安全”等行业特色。因此,在列控系统信息化、网络化的背景下,开展结合系统特点的信息安全主动防御技术研究具有重要意义。基于上述考虑,本文主要研究了列控系统信息安全建模和防御策略选取问题。将攻击对策树(Attack Countermeasure Tree,ACT)引入列控系统的攻防建模之中,修订ACT模型定义来更好地描述系统特点。在此基础上,提出了列控系统的信息安全防御目标,并给出最优主动防御策略的选取方法。论文的具体研究内容如下:(1)研究了当前工控和列控系统信息安全的现状。以采用无线局域网(Wireless Local Area Networks,WLANs)的基于通信的列车控制(Communication-based Train Control,CBTC)系统为研究对象,重点分析列控系统信息安全相关内容,包括信息安全需求、系统网络脆弱性、攻击面、典型攻防技术,尤其是主动防御技术。(2)研究了基于攻击对策树的信息安全主动防御建模方法。首先分析了攻击树、防御树、攻击防御树、贝叶斯防御图等典型安全建模方法,指出它们的局限性。然后引入攻击对策树及其概率计算、定性分析和定量分析作为信息安全分析工具,通过修订ACT模型使其更加适合列控系统的信息安全建模,给出建模步骤。(3)提出了面向列控系统信息安全的最优策略选择方法。首先通过分析列控系统特点和需求,提出了列控系统的最优防御目标及其形式化表达,然后基于一般工控系统的攻击过程,给出面向列控系统的攻击分类。接着确定了攻防定量分析中的数值量化模型,最后给出基于定性、定量分析的最优防御策略的求解算法。(4)主动防御模型与最优防御策略选择方法的应用。通过分析基于WLAN的CBTC系统的信息流定义最小系统作为分析对象,建立ACT模型,通过对模型的具体量化来求解列控系统中考虑安全和效率的最优策略,并验证防御效果。分析结果表明,本文给出的结合攻击对策树的列控系统主动防御模型能够很好地反映列控系统攻击、检测和缓解事件的交互关系,提出的防御目标和最优策略选取方法能高效地求出符合系统安全和效率目标的最优策略,并能实现多目标的优化,实验结果证明了这一套方法具有科学性和高效性。
[Abstract]:With the increasing risk of information security in rail transit train operation control system, considering the particularity and complexity of the system, the information security solution of general industrial control system can not be applied to train control system well. At present, the research on information security defense technology of train control system at home and abroad is few and deep, and the characteristics of data driving of train control system are not fully considered. Defense does not combine industry features such as Safety redundancy and Fault-Security. Therefore, under the background of information and network of train control system, it is of great significance to study the active defense technology of information security combined with the characteristics of the system. Based on the above considerations, this paper mainly studies information security modeling and defense policy selection of train control systems. The attack game tree (Attack Countermeasure tree is introduced into the attack and defense modeling of train control system, and the definition of ACT model is revised to better describe the characteristics of the system. On this basis, the information security defense target of train control system is proposed, and the method of selecting optimal active defense strategy is given. The main contents of this paper are as follows: (1) the current situation of information security in industrial control and train control systems is studied. Taking the communication based train control (Communication-based Train) system based on WLAN (Wireless Local Area Networks as the research object, the information security related contents of train control system, including information security requirements, system network vulnerability, attack surface, are analyzed emphatically. Typical attack and defense technology, especially active defense technology. (2) Information security active defense modeling method based on attack game tree is studied. Firstly, the typical security modeling methods such as attack tree, defense tree, attack defense tree and Bayesian defense graph are analyzed, and their limitations are pointed out. Then the attack game tree and its probability calculation, qualitative analysis and quantitative analysis are introduced as information security analysis tools, and the ACT model is modified to make it more suitable for the information security modeling of train control system. The modeling steps are given. (3) an optimal policy selection method for information security of train control systems is proposed. Firstly, by analyzing the characteristics and requirements of train control system, the optimal defense target and its formal expression of train control system are put forward, and then based on the attack process of general industrial control system, the attack classification to train control system is given. Then the numerical model of quantitative analysis of attack and defense is determined. Finally, the algorithm of solving the optimal defense strategy based on qualitative and quantitative analysis is given. (4) the application of active defense model and optimal defense strategy selection method. By analyzing the minimum information flow definition system of CBTC system based on WLAN as the analysis object, the ACT model is established, and the optimal strategy considering security and efficiency in the train control system is solved by quantifying the model, and the defense effect is verified. The analysis results show that the active defense model of train control system based on attack game tree presented in this paper can well reflect the interaction of train control system attack, detection and mitigation events. The proposed defense target and optimal strategy selection method can efficiently find out the optimal strategy which accords with the system security and efficiency goals, and can realize the multi-objective optimization. The experimental results show that the proposed method is scientific and efficient.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U284.48;TP309

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