Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> In this paper we attempt to answer two questions: (1) Why should we be interested in the security of control systems? And (2) What are the new and fundamentally different requirements and problems for the security of control systems? We also propose a new mathematical framework to analyze attacks against control systems. Within this framework we formulate specific research problems to (1) detect attacks, and (2) survive attacks. <s> BIB001 </s> Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> The smart grid, generally referred to as the next-generation power electric system, relies on robust communication networks to provide efficient, secure, and reliable information delivery. Thus, the network security is of critical importance in the smart grid. In this paper, we aim at classifying and evaluating the security threats on the communication networks in the smart grid. Based on a top-down analysis, we categorize the goals of potential attacks against the smart grid communication networks into three types: network availability, data integrity and information privacy. We then qualitatively analyze both the impact and feasibility of the three types of attacks. Moreover, since network availability is the top priority in the security objectives for the smart grid, we use experiments to quantitatively evaluate the impact of denial-of-service (DoS) attacks on a power substation network. Our work provides initial experimental data of DoS attacks against a power network and shows that the network performance degrades dramatically only when the DoS attack intensity approaches to the maximum. <s> BIB002 </s> Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> A power grid is a complex system connecting electric power generators to consumers through power transmission and distribution networks across a large geographical area. System monitoring is necessary to ensure the reliable operation of power grids, and state estimation is used in system monitoring to best estimate the power grid state through analysis of meter measurements and power system models. Various techniques have been developed to detect and identify bad measurements, including interacting bad measurements introduced by arbitrary, nonrandom causes. At first glance, it seems that these techniques can also defeat malicious measurements injected by attackers. In this article, we expose an unknown vulnerability of existing bad measurement detection algorithms by presenting and analyzing a new class of attacks, called false data injection attacks, against state estimation in electric power grids. Under the assumption that the attacker can access the current power system configuration information and manipulate the measurements of meters at physically protected locations such as substations, such attacks can introduce arbitrary errors into certain state variables without being detected by existing algorithms. Moreover, we look at two scenarios, where the attacker is either constrained to specific meters or limited in the resources required to compromise meters. We show that the attacker can systematically and efficiently construct attack vectors in both scenarios to change the results of state estimation in arbitrary ways. We also extend these attacks to generalized false data injection attacks, which can further increase the impact by exploiting measurement errors typically tolerated in state estimation. We demonstrate the success of these attacks through simulation using IEEE test systems, and also discuss the practicality of these attacks and the real-world constraints that limit their effectiveness. <s> BIB003 </s> Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> In this paper, we analyze several cyber-security incidents involving critical infrastructure and SCADA systems. We classify these incidents based on Source Sector, Method of Operations, Impact, and Target Sector. Using this standardized taxonomy we can easily compare and contrast current and future SCADA incidents. <s> BIB004 </s> Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> The Smart Grid, generally referred to as the next-generation power system, is considered as a revolutionary and evolutionary regime of existing power grids. More importantly, with the integration of advanced computing and communication technologies, the Smart Grid is expected to greatly enhance efficiency and reliability of future power systems with renewable energy resources, as well as distributed intelligence and demand response. Along with the silent features of the Smart Grid, cyber security emerges to be a critical issue because millions of electronic devices are inter-connected via communication networks throughout critical power facilities, which has an immediate impact on reliability of such a widespread infrastructure. In this paper, we present a comprehensive survey of cyber security issues for the Smart Grid. Specifically, we focus on reviewing and discussing security requirements, network vulnerabilities, attack countermeasures, secure communication protocols and architectures in the Smart Grid. We aim to provide a deep understanding of security vulnerabilities and solutions in the Smart Grid and shed light on future research directions for Smart Grid security. <s> BIB005 </s> Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> The concept of Multistep Electricity Price (MEP) policy has been introduced by many countries to promote energy saving, load balance and fairness in electricity consumption. However, with the development of smart grid, how to determine the electricity quantity and price scaled to multiple steps has not been fully investigated. To address this issue, in this paper we study a two-dimensional MEP model to formally analyze and determine the desirable electricity quantity and price in multiple steps. In this model, the step is scaled by both electricity quantity and the time when the electricity is used. Based on the proposed MEP model, we further investigate the vulnerability of the electricity market operation and investigate false data injection attacks against electricity price and charges to consumers. Through simulation study, our data show that the proposed MEP models can achieve the fairness in electricity consumption, balance in load between peak time and non-peak time and improvement of resource utilization. Our data also indicates that false data injection attacks can only partially compromise prices in the MEP model, leading to a limited impact on users' charges. <s> BIB006 </s> Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> It is critical for a power system to estimate its operation state based on meter measurements in the field and the configuration of power grid networks. Recent studies show that the adversary can bypass the existing bad data detection schemes, posing dangerous threats to the operation of power grid systems. Nevertheless, two critical issues remain open: 1) how can an adversary choose the meters to compromise to cause the most significant deviation of the system state estimation, and 2) how can a system operator defend against such attacks? To address these issues, we first study the problem of finding the optimal attack strategy--i.e., a data-injection attacking strategy that selects a set of meters to manipulate so as to cause the maximum damage. We formalize the problem and develop efficient algorithms to identify the optimal meter set. We implement and test our attack strategy on various IEEE standard bus systems, and demonstrate its superiority over a baseline strategy of random selections. To defend against false data-injection attacks, we propose a protection-based defense and a detection-based defense, respectively. For the protection-based defense, we identify and protect critical sensors and make the system more resilient to attacks. For the detection-based defense, we develop the spatial-based and temporal-based detection schemes to accurately identify data-injection attacks. <s> BIB007 </s> Cyber-Physical Systems Security—A Survey <s> TABLE V SMART CARS CYBER-PHYSICAL ATTACKS <s> State estimation is a very critical component in smart grid, a typical energy-based cyber-physical system. Kalman filter has been widely used in the dynamic state estimation of power systems. Although a large number of research efforts have been made on the robustness and filtering effectiveness, little effort has been conducted on cyber attacks against Kalman filtering. To address this issue, in this paper we systematically compare three representative Kalman filtering techniques and formalize the problem of anomaly detection against false data injection attacks in Kalman filter. On the basis of our modeling results, we investigate five novel attack approaches that can bypass the anomaly detection. To defend against those attacks, we develop two countermeasures: the enhancement of Kalman filtering and the temporal-based detection algorithm. We conduct extensive performance evaluation and our data validates our theoretical finding well. Copyright © 2013 John Wiley & Sons, Ltd. <s> BIB008
c) Unintentional attack: Although software updates are critical to ensuring systems are vulnerability-free, it can be a source of service disruption. For example, in a nuclear plant, one computer in the control center was updated and rebooted thereafter. The reboot erased critical data on the control system. As the data was erased, other components of the system misinterpreted such loss, resulting in abnormality in operations and the plant's shutdown BIB001 . d) Web-based attacks: Night Dragon attack, in 2011, targeted sensitive information from private networks of a number of energy and oil companies  . The attack combined a number of Web-related vectors to succeed such as SQL injection vulnerability and a malware injection  , BIB004 . 2) Smart Grids Attacks: a) DoS: The traffic in smart grids is time-critical, so delays may result in undesired consequences. Flooding the network at different layers is the probable approach to achieve DoS attacks. Lu et al. BIB002 evaluated the impact of DoS on smart grids' substations. The authors found that the network performance only gets affected if the flooding is overwhelming. In addition, at the physical layer, the deployment of wireless communications increases and therefore, jamming attacks are possible as shown in  . b) False data injection: Introducing false data in smart grids' traffic leads to different consequences such as service disruption and financial losses. Liu et al. BIB003 demonstrated a simulated false data injection (FDI) to evaluate the impact on the state estimation in smart grids. The authors assumed the attacker's preintrusion to the control center for a successful attack, which aimed to ultimately inject false measurements to smart meters to disrupt the state estimate process. Such disruption leads to financial losses for the operating utilities BIB005 . Other FDI attacks on the data integrity are proposed in BIB006 , BIB008 , and BIB007 .