With the rapid development of science and technology and the continuous fusion of industrialization and informatization, industrial control systems (ICSs) are more and more adopting standard, universal communication protocols and software/hardware systems, and being connected to the Internet in various manners. It breaks the original closure and exclusiveness of these systems, and causes security threats (such as viruses and trojans) to spread promptly into the field of industrial control. ICSs are encountered with increasingly serious information security threats that show different features from those of traditional IT systems. To briefly introduce the new trends and achievements in the field of ICS security research today, this paper presents the definition and 3-level architecture of ICSs, brings in the problem of ICS security, and elaborates the distribution and tendency of the security problem by detailed data. After that, this paper focuses on introducing the international conference ICS-CSR that is dedicated to the field of ICS information security from the viewpoint of academic research. By comparing the papers collected in the first and second ICS-CSR conferences, this paper investigates in detail on the issues of attackers and attack vectors, detection and response of cyber attacks, security modeling and vulnerability analysis of systems, and the socio-technical nature of ICSs, summarizes the main problems, ideas, approaches and conclusions in the research of ICS security, and presents the current situation and future direction of this field. Finally, this paper proposes the security concept of defense-in-depth, according to which a comprehensive defending system composed of boundary system, protection system and safety system is established aiming to provide ICSs with omni-directional, multi-layered and whole life-circle protection.
