The federated Cloud paradigm aims to provide flexible and reliable services composed of a mixture of internal and external mini-clouds, but this heterogeneous nature is also fuelling the security concerns of the customers. To allay the fears and deal with the threats associated with outsourcing data and applications to the Cloud, new methods for security assurance are urgently needed. This paper presents current work on Cloud Security Service Level Agreements and our approach on how to manage this in the context of hybrid clouds. The purpose is to facilitate rapid service composition and agreements based on the necessary security requirements and establish trust between the customer and provider.We also show how this can be applied on a realistic case study related to a hybrid Unified Communication service.

Abstract

Attack-defense trees can be used as part of threat and risk analysis for system development and maintenance. They are an extension of attack trees with defense measures. Moreover, tree nodes can be decorated with attributes, such as probability, impact and penalty, to increase the expressiveness of the model. Attribute values are typically assigned based on cognitive estimations and historically recorded events. This paper presents a practical case study with attack-defense trees. First, we create an attack-defense tree for an RFID-based goods management system for a warehouse. Then, we explore how to use a rich set of attributes for attack and defense nodes and how to assign and aggregate values to obtain condensed information, such as performance indicators or other key security figures. We discuss different modeling choices and trade-offs. The case study led us to define concrete guidelines that can be used by software developers, security analysts and system owners when performing similar assessments.

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Safety and security risks are usually analyzed independently, by different people using different tools. Consequently, the system analyst may fail to realize cyber attacks as a contributing factor to safety impacts or, on the contrary, design overly secure systems that will compromise the performance of critical operations. This paper presents a methodology for visualizing and assessing security risks by means of bow-tie diagrams, which are commonly used within safety assessments. We outline how malicious activities, random failures, security countermeasures and safety barriers can be visualized using a common graphical notation and propose a method for quantifying risks based on threat likelihood and consequence severity. The methodology is demonstrated using a case study from maritime communication. Our main conclusion is that adding security concepts to the bow-ties is a promising approach, since this is a notation that high-risk industries are already familiar with. However, their advantage as easy-to-grasp visual models should be maintained, hence complexity needs to be kept low.