Biblio

Filters: Keyword is CPS Resilience  [Clear All Filters]
2021-05-25
Ramasubramanian, Bhaskar, Niu, Luyao, Clark, Andrew, Bushnell, Linda, Poovendran, Radha.  2020.  Privacy-Preserving Resilience of Cyber-Physical Systems to Adversaries. 2020 59th IEEE Conference on Decision and Control (CDC). :3785–3792.

A cyber-physical system (CPS) is expected to be resilient to more than one type of adversary. In this paper, we consider a CPS that has to satisfy a linear temporal logic (LTL) objective in the presence of two kinds of adversaries. The first adversary has the ability to tamper with inputs to the CPS to influence satisfaction of the LTL objective. The interaction of the CPS with this adversary is modeled as a stochastic game. We synthesize a controller for the CPS to maximize the probability of satisfying the LTL objective under any policy of this adversary. The second adversary is an eavesdropper who can observe labeled trajectories of the CPS generated from the previous step. It could then use this information to launch other kinds of attacks. A labeled trajectory is a sequence of labels, where a label is associated to a state and is linked to the satisfaction of the LTL objective at that state. We use differential privacy to quantify the indistinguishability between states that are related to each other when the eavesdropper sees a labeled trajectory. Two trajectories of equal length will be differentially private if they are differentially private at each state along the respective trajectories. We use a skewed Kantorovich metric to compute distances between probability distributions over states resulting from actions chosen according to policies from related states in order to quantify differential privacy. Moreover, we do this in a manner that does not affect the satisfaction probability of the LTL objective. We validate our approach on a simulation of a UAV that has to satisfy an LTL objective in an adversarial environment.

Fauser, Moritz, Zhang, Ping.  2020.  Resilience of Cyber-Physical Systems to Covert Attacks by Exploiting an Improved Encryption Scheme. 2020 59th IEEE Conference on Decision and Control (CDC). :5489—5494.
In recent years, the integration of encryption schemes into cyber-physical systems (CPS) has attracted much attention to improve the confidentiality of sensor signals and control input signals sent over the network. However, in principle an adversary can still modify the sensor signals and the control input signals, even though he does not know the concrete values of the signals. In this paper, we shall first show that a standard encryption scheme can not prevent some sophisticated attacks such as covert attacks, which remain invisible in the CPS with encrypted communication and a conventional diagnosis system. To cope with this problem, an improved encryption scheme is proposed to mask the communication and to cancel the influence of the attack signal out of the system. The basic idea is to swap the plaintext and the generated random value in the somewhat homomorphic encryption scheme to prevent a direct access of the adversary to the transmitted plaintext. It will be shown that the CPS with the improved encryption scheme is resilient to covert attacks. The proposed encryption scheme and the CPS structure are finally illustrated through the well-established quadruple-tank process.
Barbeau, Michel, Cuppens, Frédéric, Cuppens, Nora, Dagnas, Romain, Garcia-Alfaro, Joaquin.  2020.  Metrics to Enhance the Resilience of Cyber-Physical Systems. 2020 IEEE 19th International Conference on Trust, Security and Privacy in Computing and Communications (TrustCom). :1167—1172.
We focus on resilience towards covert attacks on Cyber-Physical Systems (CPS). We define the new k-steerability and l-monitorability control-theoretic concepts. k-steerability reflects the ability to act on every individual plant state variable with at least k different groups of functionally diverse input signals. l-monitorability indicates the ability to monitor every individual plant state variable with £ different groups of functionally diverse output signals. A CPS with k-steerability and l-monitorability is said to be (k, l)-resilient. k and l, when both greater than one, provide the capability to mitigate the impact of covert attacks when some signals, but not all, are compromised. We analyze the influence of k and l on the resilience of a system and the ability to recover its state when attacks are perpetrated. We argue that the values of k and l can be augmented by combining redundancy and diversity in hardware and software techniques that apply the moving target paradigm.
Bosio, Alberto, Canal, Ramon, Di Carlo, Stefano, Gizopoulos, Dimitris, Savino, Alessandro.  2020.  Cross-Layer Soft-Error Resilience Analysis of Computing Systems. 2020 50th Annual IEEE-IFIP International Conference on Dependable Systems and Networks-Supplemental Volume (DSN-S). :79—79.
In a world with computation at the epicenter of every activity, computing systems must be highly resilient to errors even if miniaturization makes the underlying hardware unreliable. Techniques able to guarantee high reliability are associated to high costs. Early resilience analysis has the potential to support informed design decisions to maximize system-level reliability while minimizing the associated costs. This tutorial focuses on early cross-layer (hardware and software) resilience analysis considering the full computing continuum (from IoT/CPS to HPC applications) with emphasis on soft errors.
Hopkins, Stephen, Kalaimannan, Ezhil, John, Caroline Sangeetha.  2020.  Cyber Resilience using State Estimation Updates Based on Cyber Attack Matrix Classification. 2020 IEEE Kansas Power and Energy Conference (KPEC). :1—6.
Cyber-physical systems (CPS) maintain operation, reliability, and safety performance using state estimation and control methods. Internet connectivity and Internet of Things (IoT) devices are integrated with CPS, such as in smart grids. This integration of Operational Technology (OT) and Information Technology (IT) brings with it challenges for state estimation and exposure to cyber-threats. This research establishes a state estimation baseline, details the integration of IT, evaluates the vulnerabilities, and develops an approach for detecting and responding to cyber-attack data injections. Where other approaches focus on integration of IT cyber-controls, this research focuses on development of classification tools using data currently available in state estimation methods to quantitatively determine the presence of cyber-attack data. The tools may increase computational requirements but provide methods which can be integrated with existing state estimation methods and provide for future research in state estimation based cyber-attack incident response. A robust cyber-resilient CPS includes the ability to detect and classify a cyber-attack, determine the true system state, and respond to the cyber-attack. The purpose of this paper is to establish a means for a cyber aware state estimator given the existence of sub-erroneous outlier detection, cyber-attack data weighting, cyber-attack data classification, and state estimation cyber detection.
Nazemi, Mostafa, Dehghanian, Payman, Alhazmi, Mohannad, Wang, Fei.  2020.  Multivariate Uncertainty Characterization for Resilience Planning in Electric Power Systems. 2020 IEEE/IAS 56th Industrial and Commercial Power Systems Technical Conference (I CPS). :1—8.
Following substantial advancements in stochastic classes of decision-making optimization problems, scenario-based stochastic optimization, robust\textbackslashtextbackslash distributionally robust optimization, and chance-constrained optimization have recently gained an increasing attention. Despite the remarkable developments in probabilistic forecast of uncertainties (e.g., in renewable energies), most approaches are still being employed in a univariate framework which fails to unlock a full understanding on the underlying interdependence among uncertain variables of interest. In order to yield cost-optimal solutions with predefined probabilistic guarantees, conditional and dynamic interdependence in uncertainty forecasts should be accommodated in power systems decision-making. This becomes even more important during the emergencies where high-impact low-probability (HILP) disasters result in remarkable fluctuations in the uncertain variables. In order to model the interdependence correlation structure between different sources of uncertainty in power systems during both normal and emergency operating conditions, this paper aims to bridge the gap between the probabilistic forecasting methods and advanced optimization paradigms; in particular, perdition regions are generated in the form of ellipsoids with probabilistic guarantees. We employ a modified Khachiyan's algorithm to compute the minimum volume enclosing ellipsoids (MVEE). Application results based on two datasets on wind and photovoltaic power are used to verify the efficiency of the proposed framework.
Segovia, Mariana, Rubio-Hernan, Jose, Cavalli, Ana R., Garcia-Alfaro, Joaquin.  2020.  Cyber-Resilience Evaluation of Cyber-Physical Systems. 2020 IEEE 19th International Symposium on Network Computing and Applications (NCA). :1—8.
Cyber-Physical Systems (CPS) use computational resources to control physical processes and provide critical services. For this reason, an attack in these systems may have dangerous consequences in the physical world. Hence, cyber- resilience is a fundamental property to ensure the safety of the people, the environment and the controlled physical processes. In this paper, we present metrics to quantify the cyber-resilience level based on the design, structure, stability, and performance under the attack of a given CPS. The metrics provide reference points to evaluate whether the system is better prepared or not to face the adversaries. This way, it is possible to quantify the ability to recover from an adversary using its mathematical model based on actuators saturation. Finally, we validate our approach using a numeric simulation on the Tennessee Eastman control challenge problem.
Ouchani, Samir, Khebbeb, Khaled, Hafsi, Meriem.  2020.  Towards Enhancing Security and Resilience in CPS: A Coq-Maude based Approach. 2020 IEEE/ACS 17th International Conference on Computer Systems and Applications (AICCSA). :1—6.
Cyber-Physical Systems (CPS) have gained considerable interest in the last decade from both industry and academia. Such systems have proven particularly complex and provide considerable challenges to master their design and ensure their functionalities. In this paper, we intend to tackle some of these challenges related to the security and the resilience of CPS at the design level. We initiate a CPS modeling approach to specify such systems structure and behaviors, analyze their inherent properties and to overcome threats in terms of security and correctness. In this initiative, we consider a CPS as a network of entities that communicate through physical and logical channels, and which purpose is to achieve a set of tasks expressed as an ordered tree. Our modeling approach proposes a combination of the Coq theorem prover and the Maude rewriting system to ensure the soundness and correctness of CPS design. The introduced solution is illustrated through an automobile manufacturing case study.
2021-04-09
Lyshevski, S. E., Aved, A., Morrone, P..  2020.  Information-Centric Cyberattack Analysis and Spatiotemporal Networks Applied to Cyber-Physical Systems. 2020 IEEE Microwave Theory and Techniques in Wireless Communications (MTTW). 1:172—177.

Cyber-physical systems (CPS) depend on cybersecurity to ensure functionality, data quality, cyberattack resilience, etc. There are known and unknown cyber threats and attacks that pose significant risks. Information assurance and information security are critical. Many systems are vulnerable to intelligence exploitation and cyberattacks. By investigating cybersecurity risks and formal representation of CPS using spatiotemporal dynamic graphs and networks, this paper investigates topics and solutions aimed to examine and empower: (1) Cybersecurity capabilities; (2) Information assurance and system vulnerabilities; (3) Detection of cyber threat and attacks; (4) Situational awareness; etc. We introduce statistically-characterized dynamic graphs, novel entropy-centric algorithms and calculi which promise to ensure near-real-time capabilities.

2021-05-25
Ravikumar, Gelli, Hyder, Burhan, Govindarasu, Manimaran.  2020.  Next-Generation CPS Testbed-based Grid Exercise - Synthetic Grid, Attack, and Defense Modeling. 2020 Resilience Week (RWS). :92—98.
Quasi-Realistic cyber-physical system (QR-CPS) testbed architecture and operational environment are critical for testing and validating various cyber attack-defense algorithms for the wide-area resilient power systems. These QR-CPS testbed environments provide a realistic platform for conducting the Grid Exercise (GridEx), CPS security training, and attack-defense exercise at a broader scale for the cybersecurity of Energy Delivery Systems. The NERC has established a tabletop based GridEx platform for the North American power utilities to demonstrate how they would respond to and recover from cyber threats and incidents. The NERC-GridEx is a bi-annual activity with tabletop attack injects and incidence response management. There is a significant need to build a testbed-based hands-on GridEx for the utilities by leveraging the CPS testbeds, which imitates the pragmatic CPS grid environment. We propose a CPS testbed-based Quasi-Realistic Grid Exercise (QR-GridEx), which is a model after the NERC's tabletop GridEx. We have designed the CPS testbed-based QR-GridEx into two parts. Part-I focuses on the modeling of synthetic grid models for the utilities, including SCADA and WAMS communications, and attack-and-defense software systems; and the Part-II focuses on the incident response management and risk-based CPS grid investment strategies. This paper presents the Part-I of the CPS testbed-based QRGridEx, which includes modeling of the synthetic grid models in the real-time digital simulator, stealthy, and coordinated cyberattack vectors, and integration of intrusion/anomaly detection systems. We have used our existing HIL CPS security testbed to demonstrate the testbed-based QR-GridEx for a Texas-2000 bus US synthetic grid model and the IEEE-39 bus grid models. The experiments demonstrated significant results by 100% real-time performance with zero overruns for grid impact characteristics against stealthy and coordinated cyberattack vectors.
2020-10-05
Murino, Giuseppina, Armando, Alessandro, Tacchella, Armando.  2019.  Resilience of Cyber-Physical Systems: an Experimental Appraisal of Quantitative Measures. 2019 11th International Conference on Cyber Conflict (CyCon). 900:1–19.
Cyber-Physical Systems (CPSs) interconnect the physical world with digital computers and networks in order to automate production and distribution processes. Nowadays, most CPSs do not work in isolation, but their digital part is connected to the Internet in order to enable remote monitoring, control and configuration. Such a connection may offer entry-points enabling attackers to gain control silently and exploit access to the physical world at the right time to cause service disruption and possibly damage to the surrounding environment. Prevention and monitoring measures can reduce the risk brought by cyber attacks, but the residual risk can still be unacceptably high in critical infrastructures or services. Resilience - i.e., the ability of a system to withstand adverse events while maintaining an acceptable functionality - is therefore a key property for such systems. In our research, we seek a model-free, quantitative, and general-purpose evaluation methodology to extract resilience indexes from, e.g., system logs and process data. While a number of resilience metrics have already been put forward, little experimental evidence is available when it comes to the cyber security of CPSs. By using the model of a real wastewater treatment plant, and simulating attacks that tamper with a critical feedback control loop, we provide a comparison between four resilience indexes selected through a thorough literature review involving over 40 papers. Our results show that the selected indexes differ in terms of behavior and sensitivity with respect to specific attacks, but they can all summarize and extract meaningful information from bulky system logs. Our evaluation includes an approach for extracting performance indicators from observed variables which does not require knowledge of system dynamics; and a discussion about combining resilience indexes into a single system-wide measure is included. 11The authors wish to thank Leonardo S.p.A. for its financial support. The research herein presented is partially supported by project NEFERIS awarded by the Italian Ministry of Defense to Leonardo S.p.A. in partnership with the University of Genoa. This work received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 830892 for project SPARTA.
2020-07-06
Xu, Zhiheng, Ng, Daniel Jun Xian, Easwaran, Arvind.  2019.  Automatic Generation of Hierarchical Contracts for Resilience in Cyber-Physical Systems. 2019 IEEE 25th International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA). :1–11.

With the growing scale of Cyber-Physical Systems (CPSs), it is challenging to maintain their stability under all operating conditions. How to reduce the downtime and locate the failures becomes a core issue in system design. In this paper, we employ a hierarchical contract-based resilience framework to guarantee the stability of CPS. In this framework, we use Assume Guarantee (A-G) contracts to monitor the non-functional properties of individual components (e.g., power and latency), and hierarchically compose such contracts to deduce information about faults at the system level. The hierarchical contracts enable rapid fault detection in large-scale CPS. However, due to the vast number of components in CPS, manually designing numerous contracts and the hierarchy becomes challenging. To address this issue, we propose a technique to automatically decompose a root contract into multiple lower-level contracts depending on I/O dependencies between components. We then formulate a multi-objective optimization problem to search the optimal parameters of each lower-level contract. This enables automatic contract refinement taking into consideration the communication overhead between components. Finally, we use a case study from the manufacturing domain to experimentally demonstrate the benefits of the proposed framework.

Castillo, Anya, Arguello, Bryan, Cruz, Gerardo, Swiler, Laura.  2019.  Cyber-Physical Emulation and Optimization of Worst-Case Cyber Attacks on the Power Grid. 2019 Resilience Week (RWS). 1:14–18.

In this paper we report preliminary results from the novel coupling of cyber-physical emulation and interdiction optimization to better understand the impact of a CrashOverride malware attack on a notional electric system. We conduct cyber experiments where CrashOverride issues commands to remote terminal units (RTUs) that are controlling substations within a power control area. We identify worst-case loss of load outcomes with cyber interdiction optimization; the proposed approach is a bilevel formulation that incorporates RTU mappings to controllable loads, transmission lines, and generators in the upper-level (attacker model), and a DC optimal power flow (DCOPF) in the lower-level (defender model). Overall, our preliminary results indicate that the interdiction optimization can guide the design of experiments instead of performing a “full factorial” approach. Likewise, for systems where there are important dependencies between SCADA/ICS controls and power grid operations, the cyber-physical emulations should drive improved parameterization and surrogate models that are applied in scalable optimization techniques.

2020-10-05
Siddiqui, Fahad, Hagan, Matthew, Sezer, Sakir.  2019.  Establishing Cyber Resilience in Embedded Systems for Securing Next-Generation Critical Infrastructure. 2019 32nd IEEE International System-on-Chip Conference (SOCC). :218–223.

The mass integration and deployment of intelligent technologies within critical commercial, industrial and public environments have a significant impact on business operations and society as a whole. Though integration of these critical intelligent technologies pose serious embedded security challenges for technology manufacturers which are required to be systematically approached, in-line with international security regulations.This paper establish security foundation for such intelligent technologies by deriving embedded security requirements to realise the core security functions laid out by international security authorities, and proposing microarchitectural characteristics to establish cyber resilience in embedded systems. To bridge the research gap between embedded and operational security domains, a detailed review of existing embedded security methods, microarchitectures and design practises is presented. The existing embedded security methods have been found ad-hoc, passive and strongly rely on building and maintaining trust. To the best of our knowledge to date, no existing embedded security microarchitecture or defence mechanism provides continuity of data stream or security once trust has broken. This functionality is critical for embedded technologies deployed in critical infrastructure to enhance and maintain security, and to gain evidence of the security breach to effectively evaluate, improve and deploy active response and mitigation strategies. To this end, the paper proposes three microarchitectural characteristics that shall be designed and integrated into embedded architectures to establish, maintain and improve cyber resilience in embedded systems for next-generation critical infrastructure.

2020-03-02
Sahu, Abhijeet, Huang, Hao, Davis, Katherine, Zonouz, Saman.  2019.  SCORE: A Security-Oriented Cyber-Physical Optimal Response Engine. 2019 IEEE International Conference on Communications, Control, and Computing Technologies for Smart Grids (SmartGridComm). :1–6.

Automatic optimal response systems are essential for preserving power system resilience and ensuring faster recovery from emergency under cyber compromise. Numerous research works have developed such response engine for cyber and physical system recovery separately. In this paper, we propose a novel cyber-physical decision support system, SCORE, that computes optimal actions considering pure and hybrid cyber-physical states, using Markov Decision Process (MDP). Such an automatic decision making engine can assist power system operators and network administrators to make a faster response to prevent cascading failures and attack escalation respectively. The hybrid nature of the engine makes the reward and state transition model of the MDP unique. Value iteration and policy iteration techniques are used to compute the optimal actions. Tests are performed on three and five substation power systems to recover from attacks that compromise relays to cause transmission line overflow. The paper also analyses the impact of reward and state transition model on computation. Corresponding results verify the efficacy of the proposed engine.

2020-08-24
Ulrich, Jacob J., Vaagensmith, Bjorn C., Rieger, Craig G., Welch, Justin J..  2019.  Software Defined Cyber-Physical Testbed for Analysis of Automated Cyber Responses for Power System Security. 2019 Resilience Week (RWS). 1:47–54.

As the power grid becomes more interconnected the attack surface increases and determining the causes of anomalies becomes more complex. Automated responses are a mechanism which can provide resilience in a power system by responding to anomalies. An automated response system can make intelligent decisions when paired with an automated health assessment system which includes a human in the loop for making critical decisions. Effective responses can be determined by developing a matrix which considers the likely impacts on resilience if a response is taken. A testbed assists to analyze these responses and determine their effects on system resilience.

2020-10-05
Zhou, Xingyu, Li, Yi, Barreto, Carlos A., Li, Jiani, Volgyesi, Peter, Neema, Himanshu, Koutsoukos, Xenofon.  2019.  Evaluating Resilience of Grid Load Predictions under Stealthy Adversarial Attacks. 2019 Resilience Week (RWS). 1:206–212.
Recent advances in machine learning enable wider applications of prediction models in cyber-physical systems. Smart grids are increasingly using distributed sensor settings for distributed sensor fusion and information processing. Load forecasting systems use these sensors to predict future loads to incorporate into dynamic pricing of power and grid maintenance. However, these inference predictors are highly complex and thus vulnerable to adversarial attacks. Moreover, the adversarial attacks are synthetic norm-bounded modifications to a limited number of sensors that can greatly affect the accuracy of the overall predictor. It can be much cheaper and effective to incorporate elements of security and resilience at the earliest stages of design. In this paper, we demonstrate how to analyze the security and resilience of learning-based prediction models in power distribution networks by utilizing a domain-specific deep-learning and testing framework. This framework is developed using DeepForge and enables rapid design and analysis of attack scenarios against distributed smart meters in a power distribution network. It runs the attack simulations in the cloud backend. In addition to the predictor model, we have integrated an anomaly detector to detect adversarial attacks targeting the predictor. We formulate the stealthy adversarial attacks as an optimization problem to maximize prediction loss while minimizing the required perturbations. Under the worst-case setting, where the attacker has full knowledge of both the predictor and the detector, an iterative attack method has been developed to solve for the adversarial perturbation. We demonstrate the framework capabilities using a GridLAB-D based power distribution network model and show how stealthy adversarial attacks can affect smart grid prediction systems even with a partial control of network.
Fowler, Stuart, Sitnikova, Elena.  2019.  Toward a framework for assessing the cyber-worthiness of complex mission critical systems. 2019 Military Communications and Information Systems Conference (MilCIS). :1–6.
Complex military systems are typically cyber-physical systems which are the targets of high level threat actors, and must be able to operate within a highly contested cyber environment. There is an emerging need to provide a strong level of assurance against these threat actors, but the process by which this assurance can be tested and evaluated is not so clear. This paper outlines an initial framework developed through research for evaluating the cyber-worthiness of complex mission critical systems using threat models developed in SysML. The framework provides a visual model of the process by which a threat actor could attack the system. It builds on existing concepts from system safety engineering and expands on how to present the risks and mitigations in an understandable manner.
2020-07-06
Hasan, Kamrul, Shetty, Sachin, Hassanzadeh, Amin, Ullah, Sharif.  2019.  Towards Optimal Cyber Defense Remediation in Cyber Physical Systems by Balancing Operational Resilience and Strategic Risk. MILCOM 2019 - 2019 IEEE Military Communications Conference (MILCOM). :1–8.

A prioritized cyber defense remediation plan is critical for effective risk management in cyber-physical systems (CPS). The increased integration of Information Technology (IT)/Operational Technology (OT) in CPS has to lead to the need to identify the critical assets which, when affected, will impact resilience and safety. In this work, we propose a methodology for prioritized cyber risk remediation plan that balances operational resilience and economic loss (safety impacts) in CPS. We present a platform for modeling and analysis of the effect of cyber threats and random system faults on the safety of CPS that could lead to catastrophic damages. We propose to develop a data-driven attack graph and fault graph-based model to characterize the exploitability and impact of threats in CPS. We develop an operational impact assessment to quantify the damages. Finally, we propose the development of a strategic response decision capability that proposes optimal mitigation actions and policies that balances the trade-off between operational resilience (Tactical Risk) and Strategic Risk.

2020-10-05
McDermott, Thomas Allen.  2019.  A Rigorous System Engineering Process for Resilient Cyber-Physical Systems Design. 2019 International Symposium on Systems Engineering (ISSE). :1–8.
System assurance is the justified confidence that a system functions as intended and is free of exploitable vulnerabilities, either intentionally or unintentionally designed or inserted as part of the system at any time during the life cycle. The computation and communication backbone of Internet of Things (IoT) devices and other cyber-physical systems (CPS) makes them vulnerable to classes of threats previously not relevant for many physical control and computational systems. The design of resilient IoT systems encompasses vulnerabilities to adversarial disruption (Security), behavior in an operational environments (Function), and increasing interdependencies (Connectedness). System assurance can be met only through a comprehensive and aggressive systems engineering approach. Engineering methods to "design in" security have been explored in the United States through two separate research programs, one through the Systems Engineering Research Center (SERC) and one through the Defense Advanced Research Process Agency (DARPA). This paper integrates these two programs and discusses how assurance practices can be improved using new system engineering and system design strategies that rely on both functional and formal design methods.
2019-02-14
Kong, F., Xu, M., Weimer, J., Sokolsky, O., Lee, I..  2018.  Cyber-Physical System Checkpointing and Recovery. 2018 ACM/IEEE 9th International Conference on Cyber-Physical Systems (ICCPS). :22-31.

Transitioning to more open architectures has been making Cyber-Physical Systems (CPS) vulnerable to malicious attacks that are beyond the conventional cyber attacks. This paper studies attack-resilience enhancement for a system under emerging attacks in the environment of the controller. An effective way to address this problem is to make system state estimation accurate enough for control regardless of the compromised components. This work follows this way and develops a procedure named CPS checkpointing and recovery, which leverages historical data to recover failed system states. Specially, we first propose a new concept of physical-state recovery. The essential operation is defined as rolling the system forward starting from a consistent historical system state. Second, we design a checkpointing protocol that defines how to record system states for the recovery. The protocol introduces a sliding window that accommodates attack-detection delay to improve the correctness of stored states. Third, we present a use case of CPS checkpointing and recovery that deals with compromised sensor measurements. At last, we evaluate our design through conducting simulator-based experiments and illustrating the use of our design with an unmanned vehicle case study.

2020-10-06
Marquis, Victoria, Ho, Rebecca, Rainey, William, Kimpel, Matthew, Ghiorzi, Joseph, Cricchi, William, Bezzo, Nicola.  2018.  Toward attack-resilient state estimation and control of autonomous cyber-physical systems. 2018 Systems and Information Engineering Design Symposium (SIEDS). :70—75.

This project develops techniques to protect against sensor attacks on cyber-physical systems. Specifically, a resilient version of the Kalman filtering technique accompanied with a watermarking approach is proposed to detect cyber-attacks and estimate the correct state of the system. The defense techniques are used in conjunction and validated on two case studies: i) an unmanned ground vehicle (UGV) in which an attacker alters the reference angle and ii) a Cube Satellite (CubeSat) in which an attacker modifies the orientation of the satellite degrading its performance. Based on this work, we show that the proposed techniques in conjunction achieve better resiliency and defense capability than either technique alone against spoofing and replay attacks.

Nuqui, Reynaldo, Hong, Junho, Kondabathini, Anil, Ishchenko, Dmitry, Coats, David.  2018.  A Collaborative Defense for Securing Protective Relay Settings in Electrical Cyber Physical Systems. 2018 Resilience Week (RWS). :49—54.
Modern power systems today are protected and controlled increasingly by embedded systems of computing technologies with a great degree of collaboration enabled by communication. Energy cyber-physical systems such as power systems infrastructures are increasingly vulnerable to cyber-attacks on the protection and control layer. We present a method of securing protective relays from malicious change in protective relay settings via collaboration of devices. Each device checks the proposed setting changes of its neighboring devices for consistency and coordination with its own settings using setting rules based on relay coordination principles. The method is enabled via peer-to-peer communication between IEDs. It is validated in a cyber-physical test bed containing a real time digital simulator and actual relays that communicate via IEC 61850 GOOSE messages. Test results showed improvement in cyber physical security by using domain based rules to block malicious changes in protection settings caused by simulated cyber-attacks. The method promotes the use of defense systems that are aware of the physical systems which they are designed to secure.
Li, Zhiyi, Shahidehpour, Mohammad, Galvin, Robert W., Li, Yang.  2018.  Collaborative Cyber-Physical Restoration for Enhancing the Resilience of Power Distribution Systems. 2018 IEEE Power Energy Society General Meeting (PESGM). :1—5.

This paper sheds light on the collaborative efforts in restoring cyber and physical subsystems of a modern power distribution system after the occurrence of an extreme weather event. The extensive cyber-physical interdependencies in the operation of power distribution systems are first introduced for investigating the functionality loss of each subsystem when the dependent subsystem suffers disruptions. A resilience index is then proposed for measuring the effectiveness of restoration activities in terms of restoration rapidity. After modeling operators' decision making for economic dispatch as a second-order cone programming problem, this paper proposes a heuristic approach for prioritizing the activities for restoring both cyber and physical subsystems. In particular, the proposed heuristic approach takes into consideration of cyber-physical interdependencies for improving the operation performance. Case studies are also conducted to validate the collaborative restoration model in the 33-bus power distribution system.

Amarasinghe, Kasun, Wickramasinghe, Chathurika, Marino, Daniel, Rieger, Craig, Manicl, Milos.  2018.  Framework for Data Driven Health Monitoring of Cyber-Physical Systems. 2018 Resilience Week (RWS). :25—30.

Modern infrastructure is heavily reliant on systems with interconnected computational and physical resources, named Cyber-Physical Systems (CPSs). Hence, building resilient CPSs is a prime need and continuous monitoring of the CPS operational health is essential for improving resilience. This paper presents a framework for calculating and monitoring of health in CPSs using data driven techniques. The main advantages of this data driven methodology is that the ability of leveraging heterogeneous data streams that are available from the CPSs and the ability of performing the monitoring with minimal a priori domain knowledge. The main objective of the framework is to warn the operators of any degradation in cyber, physical or overall health of the CPS. The framework consists of four components: 1) Data acquisition and feature extraction, 2) state identification and real time state estimation, 3) cyber-physical health calculation and 4) operator warning generation. Further, this paper presents an initial implementation of the first three phases of the framework on a CPS testbed involving a Microgrid simulation and a cyber-network which connects the grid with its controller. The feature extraction method and the use of unsupervised learning algorithms are discussed. Experimental results are presented for the first two phases and the results showed that the data reflected different operating states and visualization techniques can be used to extract the relationships in data features.