Abstract-Cyber physical systems, like power plants, medical devices and data centers have to meet high standards, both in terms of safety (i.e. absence of unintentional failures) and security (i.e. no disruptions due to malicious attacks).This paper presents attack fault trees (AFTs), a formalism that marries fault trees (safety) and attack trees (security). We equip AFTs with stochastic model checking techniques, enabling a rich plethora of qualitative and quantitative analyses. Qualitative metrics pinpoint to root causes of the system failure, while quantitative metrics concern the likelihood, cost, and impact of a disruption. Examples are: (1) the most likely attack path; (2) the most costly system failure; (3) the expected impact of an attack. Each of these metrics can be constrained, i.e., we can provide the most likely disruption within time t and/or budget B. Finally, we can use sensitivity analysis to find the attack step that has the most influence on a given metric. We demonstrate our approach through three realistic cases studies.

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Attack trees (ATs) are a popular formalism for security analysis, and numerous variations and tools have been developed around them. These were mostly developed independently, and offer little interoperability or ability to combine various AT features. We present ATTop, a software bridging tool that enables automated analysis of ATs using a model-driven engineering approach. ATTop fulfills two purposes: 1. It facilitates interoperation between several AT analysis methodologies and resulting tools (e.g., ATE, ATCalc, ADTool 2.0), 2. it can perform a comprehensive analysis of attack trees by translating them into timed automata and analyzing them using the popular model checker Uppaal, and translating the analysis results back to the original ATs. Technically, our approach uses various metamodels to provide a unified description of AT variants. Based on these metamodels, we perform model transformations that allow to apply various analysis methods to an AT and trace the results back to the AT domain. We illustrate our approach on the basis of a case study from the AT literature.

Abstract. Securing automated teller machines (ATMs), as critical and complex infrastructure, requires a precise understanding of the associated threats. This paper reports on the application of attack-defense trees to model and analyze the security of ATMs. We capture the most dangerous multi-stage attack scenarios applicable to ATM structures, and establish a practical experience report, where we reflect on the process of modeling ATM threats via attack-defense trees. In particular, we share our insights into the benefits and drawbacks of attack-defense tree modeling, as well as best practices and lessons learned.

Cloud computing and smart gadgets are the need of smart world these days. This often leads to latency and irregular connectivity issues in many situations. In order to overcome this issue, an emerging technique of fog computing is used for cloud and smart devices. A decentralized computing infrastructure in which all the elements, that is, storage, compute, data and the applications in use, are passed in an efficient and logical place between cloud and the data source, is called Fog computing. The cloud computing and services are generally extended by fog computing, which brings the power and advantages of data creation and data analysis at the network edge. Real-time location based services and applications with mobility support are enabled due to the physical proximity of users and high speed internet connection to the cloud. Fog computing is promoted with leveraging load balancing techniques so as to balance the load which is done in two ways, that is, static load balancing and dynamic load balancing. In this paper, different load balancing algorithms are discussed and their comparative analysis has been carried out. Round Robin load balancing is the simplest and easiest load balancing technique to be implemented in fog computing environments. The major problem of Source IP Hash load balancing algorithm is that each change can redirect to anyone with a different server, and thus, is least preferred in fog networks. The mechanisms to make energy efficient load balancing are also considered as the part of this paper.

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