Roberto Nardone

Vulnerability modeling and analysis for critical infrastructure protection applications

Abstract Effective critical infrastructure protection requires methodologies and tools for the automated evaluation of the vulnerabilities of assets and the efficacy of protection systems. This paper presents a modeling language for vulnerability analysis in critical infrastructure protection applications. The language extends the popular Unified Modeling Language (UML) to provide vulnerability and protection modeling functionality. The extended language provides an abstract representation of concepts and activities in the infrastructure protection domain that enables model-to-model transformations for analysis purposes. The application of the language is demonstrated through a use case that models vulnerabilities and physical protection systems in a railway station.

Enabling the usage of UML in the verification of railway systems: The DAM-rail approach

The need for integration of model-based verification into industrial processes has produced several attempts to define Model-Driven solutions implementing a unifying approach to system development. A recent trend is to implement tool chains supporting the developer both in the design phase and V&V activities. In this Model-Driven context, specific domains require proper modelling approaches, especially for what concerns RAM (Reliability, Availability, Maintainability) analysis and fulfillment of international standards. This paper specifically addresses the definition of a Model-Driven approach for the evaluation of RAM attributes in railway applications to automatically generate formal models. For this aim we extend the MARTE-DAM UML profile with concepts related to maintenance aspects and service degradation, and show that the MARTE-DAM framework can be successfully specialized for the railway domain. Model transformations are then defined to generate Repairable Fault Tree and Bayesian Network models from MARTE-DAM specifications. The whole process is applied to the railway domain in two different availability studies.

Estimation of the Energy Consumption of Mobile Sensors in WSN Environmental Monitoring Applications

The increasing necessity to have wireless sensor nodes capable to be active for a long time without battery recharge asks for technologies and methods that can anticipate the level of energy drain in these devices. In this paper a modelling approach based on Fluid Stochastic Petri Nets is proposed. The main contribution of the paper is the definition of a model to estimate single node performance in presence of several energy consuming entities. The definition of this single node model is relevant in order to properly support the design of more complex network topologies. The paper also reports first experimental results on model analysis mainly conducted by simulation.

Towards Model-Driven V&V assessment of railway control systems

Verification and Validation (V&V) activities aiming at certifying railway controllers are among the most critical and time-consuming in system development life cycle. As such, they would greatly benefit from novel approaches enabling both automation and traceability for assessment purposes. While several formal and Model-Based approaches have been proposed in the scientific literature, some of which are successfully employed in industrial settings, we are still far from an integrated and unified methodology which allows guiding design choices, minimizing the chances of failures/non-compliances, and considerably reducing the overall assessment effort. To address these issues, this paper describes a Model-Driven Engineering approach which is very promising to tackle the aforementioned challenges. In fact, the usage of appropriate Unified Modeling Language profiles featuring system analysis and test case specification capabilities, together with tool chains for model transformations and analysis, seems a viable way to allow end-users to concentrate on high-level holistic models and specification of non-functional requirements (i.e., dependability) and support the automation of the V&V process. We show, through a case study belonging to the railway signalling domain, how the approach is effective in supporting activities like system testing and availability evaluation.

A simulation framework for supporting design and real-time decisional phases in railway systems

Actors of railway systems are more and more required to achieve certain levels of system performances and acceptable standards of service quality offered to passengers. To reach this aim, effects on both supply and demand-side induced by different solutions, need to be assessed within design and real-time operation phases, especially when failures occur during service. To this purpose, in this paper an integrated framework is introduced to simulate railway operation considering also interactions with passengers demand. A practical application to a MRT line has been realized, analyzing impacts of two recovery strategies for different failure scenarios. Results underline the necessity of assessing both service availability and quality of service to identify the most effective intervention solution, and highlight the relevance of the proposed framework to support decisional processes.

Dynamic State Machines for Formalizing Railway Control System Specifications

activities regulated by international standards which explicitly recommend the usage of Finite State Machines (FSMs) to model the specification of the system under test. Despite the great number of work addressing the usage of FSMs and their extensions, actual model-driven verification processes still lacks concise and expressive enough notations, able to easily capture characteristic features of specific domains. This paper introduces DSTM4Rail, a hierarchical state machines formalism to be used in verification contexts, whose peculiarity mainly resides in the semantics of fork-and-join which allows dynamic (bounded) instantiation of machines (processes). The formalism described in this paper is industry driven, as it raises from real industrial needs in the context of an European project. Hence, the proposed semantics is motivated by illustrating concrete issues in modeling specific functionalities of the Radio Block Centre, the vital core of the ERTMS/ETCS Control System.

An interoperable testing environment for ERTMS/ETCS control systems

Verification of functional requirements of critical control systems requires a hard testing activity regulated by international standards. As testing often forms more than fifty percent of the total development cost, to support the verification processes by automated solutions is a key factor for achieving lower effort and costs and reducing time to market. The ultimate goal of the ongoing work here described is the development of an interoperable testing environment supporting the system level testing of railway ERTMS/ETCS control systems. The testing environment will provide a standardized interface to enable the integration testing between sub-systems developed by different companies/suppliers. We present the first outcomes obtained within the ARTEMIS project CRYSTAL which tackles the challenge to establish and push forward an Interoperability Specification (IOS) as an open European standard for the development of safety-critical embedded systems.

An integrated approach for availability and QoS evaluation in railway systems

Prediction of service availability in railway systems requires an increasing attention by designers and operators in order to satisfy acceptable service quality levels offered to passengers. For this reason it is necessary to reach high availability standards, relying on high-dependable system components or identifying effective operational strategies addressed to mitigate failure effects. To this purpose, in this paper an innovative architecture is proposed to simulate railway operation in order to conduct different kinds of analysis. This architecture encompasses a set of components considering, in an integrated way, several system features. Finally an application to a first case study demonstrates the impact on quality of service and service availability of different recovery strategies. Complexity of a railway system requires a heterogeneous working group composed of experts in transport and in computer science areas, with the support of industry.

On synergies of cyber and physical security modelling in vulnerability assessment of railway systems

Display Omitted Cyber-physical systems need holistic methods to discover relationships between physical and cyber components.Security threats attempt to both physical and cyber elements.Model-driven techniques accounting for joint physical and cyber-security modelling and evaluation are explored.Synergies between physical and cyber security UML profiles remarked in a case study of the railway domain. The multifaceted nature of cyber-physical systems needs holistic study methods to detect essential aspects and interrelations among physical and cyber components. Like the systems themselves, security threats feature both cyber and physical elements. Although to apply divide et impera approaches helps handling system complexity, to consider just one aspect at a time does not provide adequate risk awareness and hence does not allow to design the most appropriate countermeasures. To support this claim, in this paper we provide a joint application of two model-driven techniques for physical and cyber-security evaluation. We apply two UML profiles, namely SecAM (for cyber-security) and CIP_VAM (for physical security), in combination. In such a way, we demonstrate the synergy between both profiles and the need for their tighter integration in the context of a reference case study from the railway domain.

Model-Driven v&v processes for computer based control systems: a unifying perspective

A recent trend in software engineering is to support the development process by providing flexible tool chains allowing for effective Model-Driven approaches. These solutions are very appealing in industrial settings since they enable the creation of development and verification processes, enhancing abstraction and reuse, and hence improving productivity. This paper addresses advantages and challenges in extending Model-Driven approaches to system engineering and specifically to verification and validation (V&V) of critical computer-based systems. Specifically, the paper highlights the needs for real-world industrial contexts and proposes the definition of a unifying Model-Driven process for V&V of functional and non-functional system properties. Some enabling techniques which aim at improving the reuse of Model-Driven artifacts are addressed to deal with process scalability and effectiveness. Two sample applications are described for ERTMS/ETCS signalling system in order to show the advantages of the approach: formal modeling for performance evaluation of message delivery between train and track controllers and test case generation for the verification of functional requirements of trains outdistancing.