G. Manimaran

Vulnerability Assessment of Cybersecurity for SCADA Systems

Vulnerability assessment is a requirement of NERCs cybersecurity standards for electric power systems. The purpose is to study the impact of a cyber attack on supervisory control and data acquisition (SCADA) systems. Compliance of the requirement to meet the standard has become increasingly challenging as the system becomes more dispersed in wide areas. Interdependencies between computer communication system and the physical infrastructure also become more complex as information technologies are further integrated into devices and networks. This paper proposes a vulnerability assessment framework to systematically evaluate the vulnerabilities of SCADA systems at three levels: system, scenarios, and access points. The proposed method is based on cyber systems embedded with the firewall and password models, the primary mode of protection in the power industry today. The impact of a potential electronic intrusion is evaluated by its potential loss of load in the power system. This capability is enabled by integration of a logic-based simulation method and a module for the power flow computation. The IEEE 30-bus system is used to evaluate the impact of attacks launched from outside or from within the substation networks. Countermeasures are identified for improvement of the cybersecurity.

Cybersecurity for Critical Infrastructures: Attack and Defense Modeling

Disruption of electric power operations can be catastrophic on national security and the economy. Due to the complexity of widely dispersed assets and the interdependences among computer, communication, and power infrastructures, the requirement to meet security and quality compliance on operations is a challenging issue. In recent years, the North American Electric Reliability Corporation (NERC) established a cybersecurity standard that requires utilities compliance on cybersecurity of control systems. This standard identifies several cyber-related vulnerabilities that exist in control systems and recommends several remedial actions (e.g., best practices). In this paper, a comprehensive survey on cybersecurity of critical infrastructures is reported. A supervisory control and data acquisition security framework with the following four major components is proposed: (1) real-time monitoring; (2) anomaly detection; (3) impact analysis; and (4) mitigation strategies. In addition, an attack-tree-based methodology for impact analysis is developed. The attack-tree formulation based on power system control networks is used to evaluate system-, scenario -, and leaf-level vulnerabilities by identifying the systems adversary objectives. The leaf vulnerability is fundamental to the methodology that involves port auditing or password strength evaluation. The measure of vulnerabilities in the power system control framework is determined based on existing cybersecurity conditions, and then, the vulnerability indices are evaluated.

Internet infrastructure security: a taxonomy

The pervasive and ubiquitous nature of the Internet coupled with growing concerns about cyber terrorism demand immediate solutions for securing the Internet infrastructure. So far, the research in Internet security primarily focused on. securing the information rather than securing the infrastructure itself. Given the prevailing threat situation, there is a compelling need to develop architectures, algorithms, and protocols to realize a dependable Internet infrastructure. In order to achieve this goal, the first and foremost step is to develop a comprehensive understanding of the security threats and existing solutions. This article attempts to fulfill this important step by providing a taxonomy of security attacks, which are classified into four main categories: DNS hacking, routing table poisoning, packet mistreatment, and denial-of-service attacks. The article discusses the existing solutions for each of these categories, and also outlines a methodology for developing secure protocols.

Application of Sensor Network for Secure Electric Energy Infrastructure

Wireless sensor networks are becoming the technology of choice for sensing applications mostly due to their ease of installation and associated lower costs. This paper proposes a novel conceptual design for an application of wireless sensor technology for assessing the structural health of transmission lines and their implementation to improve the observability and reliability of power systems. A two-layer sensor network model is presented for overcoming the communication range limitations of smart sensors, and two operational modes for enhanced energy efficiency are introduced. Simulations integrating the output of the sensor network with an energy-management system were conducted, obtaining improvement in the security of the power system

A survey of QoS multicasting issues

The proliferation of QoS-aware group applications over the Internet has accelerated the need for scalable and efficient multicast support. We present a multicast life cycle model that identifies the various issues involved in a typical multicast session. During the life cycle of a multicast session, three important events can occur: group dynamics, network dynamics, and traffic dynamics. The first two aspects are concerned with maintaining a good-quality (e.g., cost) multicast tree taking into account member join/leave and changes in the network topology due to link/node failures/additions, respectively. The third aspect is concerned with flow, congestion, and error control. We examine various issues and solutions for managing group dynamics and failure handling in QoS multicasting, and outline several future research directions.

An information architecture for future power systems and its reliability analysis

Analysis of 162 disturbances from 1979-1995 reported by the North American Electric Reliability Council (NERC) indicates the importance of information systems under the regulated and competitive environment. This paper points out the major deficiencies in current communication and information systems and proposes a new power system information architecture aimed at correcting these deficiencies. The proposed architecture includes automation and control systems at all levels, from substation control system to independent system operator (ISO) operating center, taking into account the requirements of real-time data, security, availability, scalability, and appropriate quality of service. It uses multiple communication channels employing a wide variety of technologies to transmit real-time operating data and control signals. The real-time operating and control system is modeled with various redundancy configurations. The reliabilities of different configurations are studied and compared for practical values of component failure rates and repair rates.

An adaptive scheme for fault-tolerant scheduling of soft real-time tasks in multiprocessor systems

The scheduling of real-time tasks with primary-backup-based fault-tolerant requirements has been an important problem for several years. Most of the known scheduling schemes are non-adaptive in nature meaning that they do not adapt to the dynamics of faults and tasks parameters in the system. In this paper, we propose an adaptive fault-tolerant scheduling scheme that has a mechanism to control the overlap interval between the primary and backup versions of tasks such that the overall performance of the system is improved. The overlap interval is determined based on the observed fault rate and tasks soft laxity. We also propose a new performance index, called SR index, that integrates schedulability (S) and reliability (R) into a single metric. To evaluate the proposed scheme, we have conducted analytical and simulation studies under different fault and deadline scenarios, and found that the proposed adaptive scheme adapts to system dynamics and offers better SR index than that of the non-adaptive schemes.

Packet scheduling with delay and loss differentiation

To support quality of service over the Internet, the Differentiated Services model has been proposed recently by the IETF. In the Differentiated Services model, flows with similar qualities of service (QoS) requirements are aggregated into classes in order to counter the scalability problem faced by the Integrated Services model. There have been several models proposed for service differentiation. The relative differentiated service model is one among them in which an assurance is given that higher classes will be better, or at least no worse, than lower classes. Packet delay and packet loss are two general quality metrics under which the differentiation can take place. In this paper, we propose three schedulers based on the relative differentiated service model, namely, delay only, loss only, and both delay and loss schedulers. To evaluate the performance of the proposed schedulers, we have conducted extensive simulation studies (both per-hop and end-to-end) under uniform and non-uniform traffic loads. Our simulation studies show that the delay only and loss only schedulers differentiate effectively only in delay and loss, respectively, and the combined delay and loss scheduler differentiates effectively in both delay and loss.

Efficient overloading techniques for primary-backup scheduling in real-time systems

In real-time systems, tasks have deadlines to be met despite the presence of faults. Primary-Backup (PB) scheme is one of the most important schemes that has been employed for fault-tolerant scheduling of real-time tasks, wherein each task has two versions and the versions are scheduled on two different processors with time exclusion. There have been techniques proposed for improving schedulability of the PB-based scheduling, of which Backup-Backup (BB) overloading is among the most popular ones. In this technique two or more backups can share/overlap in time on a processor. In this paper, we propose two new techniques that accommodate more tasks and/or tolerate faults effectively. In the first technique, called dynamic grouping, the processors are dynamically grouped into logical groups in order to achieve efficient overloading of tasks on resources, thereby improving the schedulability and the reliability of the system. In the second technique, called PB overloading, the primary of a task can share/ overlap in time with the backup of another task on a processor. The intuition is that, for a primary (or backup), the PB-overloading can assign an earlier start time than that of the BB-overloading, thereby increasing the schedulability. We conduct schedulability and reliability analysis of the proposed techniques through simulation and analytical studies. Our studies show that dynamic grouping improves the schedulability more than static grouping, and offers graceful degradation with increasing faults. Also, PB-overloading improves the schedulability more than BB-overloading, and offers reliability comparable to that of BB-overloading. The proposed techniques are generic that they can be incorporated into many fault-tolerant non-preemptive scheduling algorithms.

A new fault-tolerant technique for improving schedulability in multiprocessor real-time systems

In real-time systems, tasks have deadlines to be met despite the presence of faults. Primary-Backup (PB) scheme is one of the most common schemes that has been employed for fault-tolerant scheduling of real-time tasks, wherein each task has two versions and the versions are scheduled on two different processors with time exclusion. There have been techniques proposed for improving schedulability of the PB-based scheduling. One of the more popular ones include Backup-Backup (BB) overloading, wherein two or more backups can share/overlap in time on a processor. In this paper we propose a new schedulability enhancing technique, called primary-backup (PB) overloading, in which the primary of a task can share/overlap in time with the backup of another task an a processor. The intuition is that, for both primary and backup of a task, the PB-overloading can assign an earlier start time than that of the BB-overloading, thereby increasing the schedulability. We conduct schedulability and reliability analysis of PB- and BB-overloading techniques through simulation and analytical studies. Our studies show that PB-overloading offers better schedulability (25% increase in the guarantee ratio) than that of BB-overloading, and offers reliability comparable to that of BB-overloading. The proposed PB-overloading is a general technique that can be employed in any static or dynamic fault-tolerant scheduling algorithm.