Evaluating Resilience of Cyber-Physical-Social Systems

Nowadays, protecting the network is not the only security concern. Still, in cyber security, websites and servers are becoming more popular as targets due to the ease with which they can be accessed when compared to communication networks. Another threat in cyber physical social systems with human interactions is that they can be attacked and manipulated not only by technical hacking through networks, but also by manipulating people and stealing users’ credentials. Therefore, systems should be evaluated beyond cy- ber security, which means measuring their resilience as a piece of evidence that a system works properly under cyber-attacks or incidents. In that way, cyber resilience is increas- ingly discussed and described as the capacity of a system to maintain state awareness for detecting cyber-attacks. All the tasks for making a system resilient should proactively maintain a safe level of operational normalcy through rapid system reconfiguration to detect attacks that would impact system performance. In this work, we broadly studied a new paradigm of cyber physical social systems and defined a uniform definition of it. To overcome the complexity of evaluating cyber resilience, especially in these inhomo- geneous systems, we proposed a framework including applying Attack Tree refinements and Hierarchical Timed Coloured Petri Nets to model intruder and defender behaviors and evaluate the impact of each action on the behavior and performance of the system.Hoje em dia, proteger a rede não é a única preocupação de segurança. Ainda assim, na segurança cibernética, sites e servidores estão se tornando mais populares como alvos devido à facilidade com que podem ser acessados quando comparados às redes de comu- nicação. Outra ameaça em sistemas sociais ciberfisicos com interações humanas é que eles podem ser atacados e manipulados não apenas por hackers técnicos através de redes, mas também pela manipulação de pessoas e roubo de credenciais de utilizadores. Portanto, os sistemas devem ser avaliados para além da segurança cibernética, o que significa medir sua resiliência como uma evidência de que um sistema funciona adequadamente sob ataques ou incidentes cibernéticos. Dessa forma, a resiliência cibernética é cada vez mais discutida e descrita como a capacidade de um sistema manter a consciência do estado para detectar ataques cibernéticos. Todas as tarefas para tornar um sistema resiliente devem manter proativamente um nível seguro de normalidade operacional por meio da reconfi- guração rápida do sistema para detectar ataques que afetariam o desempenho do sistema. Neste trabalho, um novo paradigma de sistemas sociais ciberfisicos é amplamente estu- dado e uma definição uniforme é proposta. Para superar a complexidade de avaliar a resiliência cibernética, especialmente nesses sistemas não homogéneos, é proposta uma estrutura que inclui a aplicação de refinamentos de Árvores de Ataque e Redes de Petri Coloridas Temporizadas Hierárquicas para modelar comportamentos de invasores e de- fensores e avaliar o impacto de cada ação no comportamento e desempenho do sistema

Coloured Petri Nets - a Pragmatic Formal Method for Designing and Analysing Distributed Systems

The thesis consists of six individual papers, where the present paper contains the mandatory overview, while the remaining five papers are found separately from the overview. The five papers can roughly be divided into three areas of research, namely case studies, education, and extensions to the CPN method.The primary purpose of the PhD thesis is to study the pragmatics, practical aspects, and intuition of CP-nets viewed as a formal method for describing and reasoning about concurrent systems. The perspective of pragmatics is our leitmotif, but at the same time in the context of CP-nets it is a kind of hypothesis of this thesis. This overview paper summarises the research conducted as an investigation of the hypothesis in the three areas of case studies, education, and extensions.The provoking claim of pragmatics should not be underestimated. In the present overview of the thesis, the CPN method is compared with a representative selection of formal methods. The graphics and simplicity of semantics, yet generality and expressiveness of the language constructs, essentially makes CP-nets a viable and attractive alternative to other formal methods. Similar graphical formal methods, such as SDL and Statecharts, typically have significantly more complicated semantics, or are domain-specific languages.research conducted in this thesis, opens a new complex of problems. Firstly, to get wider acceptance of CP-nets in industry, it is important to identify fruitful areas for the effective introduction of the CPN method. Secondly, it would be useful to identify a few extensions to the CPN method inspired by specific domains for easier adaption in industry. Thirdly, which analysis methods do future systems make use of

Neighborhood Detection in Mobile Ad-Hoc Network Using Colored Petri Net

Colored Petri Nets (CPNs) [2] is a language for the modeling and validation of systems in which concurrency, communication [6], and synchronization play a major role. Colored Petri Nets is a discrete-event modeling language combining Petri nets with the functional programming language Standard ML. Petri nets provide the foundation of the graphical notation and the basic primitives for modeling concurrency, communication, and synchronization. Standard ML provides the primitives for the definition of data types, describing data manipulation, and for creating compact and parameterizable models. A CPN model of a system is an executable model representing the states of the system and the events (transitions) that can cause the system to change state [4]. The CPN language makes it possible to organize a model as a set of modules, and it includes a time concept for representing the time taken to execute events in the modeled system. In a mobile ad-hoc network(MANET) mobile nodes directly send messages to each other via wireless transmission. A node can send a message to another node beyond its transmission range by using other nodes as relay points, and thus a node can function as a router [1]. Typical applications of MANETS include defense systems such as battlefield survivability and disaster recovery. The research on MANETs originates from part of the Advanced Research Projects Agency(ARPA) project in the 1970s [1]. With the explosive growth of the Internet and mobile communication networks, challenging requirements have been introduced into MANETs and designing routing protocols has become more complex. One approach for ensuring correctness of an existing routing protocol is to create a formal model for the protocol and analyze the model to determine if indeed the protocol provides the defined service correctly. Colored Petri Nets are a suitable modeling language for this purpose as it can conveniently express non-determinism, concurrency and different levels of abstraction that are inherent in routing protocols. However, it is not easy to build a CPN model of a MANET because a node can move in and out of its transmission range and thus the MANET‟s topology dynamically changes. In this paper we propose an algorithm for addressing such mobility problem of a MANET [1]. Using this algorithm a node can find its neighbors ,which are dynamically changing, at any instant of time

Teaching Coloured Petri Nets - a Gentle Introduction to Formal Methods in a Distributed Systems Course

This paper is about the two compulsory project assignments set to the students in an undergraduate course on distributed systems. In the first assignment the students design and validate a non-trivial layered protocol by means of Coloured Petri Nets, and in the second they implement the designed protocol in an object-oriented language. From the two assignments the students experience that Coloured Petri Nets, as a formal method, are useful for designing and analysing distributed systems. In the course students are introduced to basic concepts and techniques for distributed systems, and it is explained that such systems are often too complex to manage without using formal methods. In this paper we also report on our experience with teaching the course and describe the didactic methods applied. Based on the obtained experience we conclude that the combination of distributed systems and Coloured Petri Nets is fruitful --- the two areas complement each other. Although our experiences origin in Coloured Petri Nets, we believe that many of our observations hold for other formal methods as well.Topics. Education issues related to nets; Coloured Petri Nets; distributed systems; experience with using nets,case studies; applications of nets to protocols

Eighth Workshop and Tutorial on Practical Use of Coloured Petri Nets and the CPN Tools, Aarhus, Denmark, October 22-24, 2007

This booklet contains the proceedings of the Eighth Workshop on Practical Use of Coloured Petri Nets and the CPN Tools, October 22-24, 2007. The workshop is organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The papers are also available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop0

Colored Petri Net: Its application to Sucrose Biosynthesis Pathway in Plasmodium falciparum

Sucrose plays major role as macromolecule used in organisms including Plasmodium falciparum (P.f.) to generate glucose for energy production in the glycolysis pathway. A metabolic pathway is a series of chemical reactions, which goes through various intermediate compounds to transform input compounds into a product. In this work, we modelled a metabolic pathway in Plasmodium falciparum using Colored Petri Net Markup Language (CPNML). The model was used to examine the dynamic behavior of the sucrose biosynthesis pathway which shows the interactions between the metabolites and the reactions in the sucrose biosynthesis pathway of Plasmodium falciparum. We further analyzed the model for its structural and quantitative properties using Petri Net theory. Our model gives more insight to the structure of the pathway and helps to improve our understanding of the biological processes within this pathway.Keywords: Sucrose, Colored Petri Net, Plasmodium falciparu

A Model Driven Approach to the Analysis of Timeliness Properties

Abstract. The need for a design language that is rigorous but accessible and intuitive is often at odds with the formal and mathematical nature of languages used for analysis. UML and Petri Nets are a good example of this dichotomy. UML is a widely accepted modelling language capable of modelling the structural and behavioural aspects of a system. However UML lacks the mathematical foundation that is required for rigorous analysis. Petri Nets on the other hand have a strong mathematical base that is well suited for analysis of a system but lacks the appeal and ease-of-use of UML. Design in UML languages such as Sequence Diagrams and analysis in Petri Nets require on one hand some expertise in potentially two incompatible systems and their tools, and on the other a seamless transition from one system to the other. One way of addressing this impediment is to focus the software development mainly on the design language system and to facilitate the transition to the formal analysis by means of a combination of automation and tool support. The aim of this paper is to present a transformation system, which takes UML Sequence Diagrams augmented with time constraints and generates semantically equivalent Petri Nets that preserve the timing requirements. A case study on a small network is used in order to illustrate the proposed approach and in particular the design, the transformation and the analysis processes.

Design/CPN - A Computer Tool for Coloured Petri Nets

In this paper, we describe the computer tool Design/CPN supporting editing, simulation, and state space analysis of Coloured Petri Nets. So far, approximately 40 man-years have been invested in the development of Design/CPN. It is used world-wide by more than 200 companies and research institutions. For the presentation, we draw from the experiences gained in recent industrial application using Coloured Petri Nets in the design, validation, and verification of communication protocols for audio/video systems

Validation of Routing Protocol for Mobile Ad Hoc Networks using Colored PetriNets

In a Mobile Ad Hoc Network (MANET), mobile nodes directly send messages to each other via other nodes in a wireless environment. A node can send a message to a destination node beyond its transmission range by using other nodes as relay points, and thus a node can function as a router. With the explosive growth of the Internet and mobile communication networks, challenging requirements have been introduced into MANETs and designing routing protocols has become more complex. For a successful application of MANETS, it is very important to ensure that a routing protocol is unambiguous, complete and functionally correct. One approach to ensuring correctness of an existing routing protocol is to create a formal model for the protocol, and analyze the model to determine if needed the protocol provides the defined service correctly. Colored Petri Nets (CPNs) are a suitable modeling language for this purpose, as it can conveniently express non-determinism , concurrency and different levels of abstraction that are inherent in routing protocols. However it is not easy to build a CPN model of a MANET because a node can move in and out of its transmission range and thus the MANET’s topology dynamically changes. So a topology approximation (TA) mechanism has been proposed to address this problem of mobility and perform simulations of routing protocol called Ad Hoc On demand Distance Vector Routing (AODV) and Distance Source Routing(DSR) and to perform comparison based on the simulation results

Validation of scenario-based business requirements with Coloured Petri Nets

A scenario can be used to describe a possible instantiation of a given business use case and can be expressed for example as a list of steps written in natural language, or by an interaction diagram. This paper discusses how a collection of scenarios, all expressed as UML2 sequence diagrams, can be described for validation purposes by a single model, written in the Coloured Petri Nets (CPN) modelling language. Due to the support for parallelism given by the CPN language, the obtained CPN model can: (1) simultaneously execute several scenarios; and (2) elegantly represent the parallel activities inside a scenario. This two-level parallelism is crucial during validation, since it allows one to detect problems that are only evident when several scenarios are in simultaneous execution and may affect each other. We exemplify our approach in a system that has a rich set of interactions with its users.Fundação para a Ciência e a Tecnologia (FCT) - bolsa SFRH/BD/19718/2004, programa PTDC/EIA/70271/2006 “AMADEUS: Aspects and Compiler Optimizations for Matlab System Development