Biblio

Mobile terminals especially smartphones are changing people's work and life style. For example, mobile payments are experiencing rapid growth as consumers use mobile terminals as part of lifestyles. However, security is a big challenge for mobile application services. In order to reduce security risks, mobile terminal security assessment should be conducted before providing application services. An approach of comprehensive security assessment is proposed in this paper by defining security metrics with the corresponding scores and determining the relative weights of security metrics based on the analytical hierarchy process (AHP). Overall security assessment of Android-based mobile terminals is implemented for mobile payment services with payment fraud detection accuracy of 89%, which shows that the proposed approach of security assessment is reasonable.

The need to achieve a suitable level of security in Cyber-Physical Systems (CPS) presents a major challenge for engineers. The unpredictable communication of highly constrained, but safety-relevant systems in a heterogeneous environment, significantly impacts the number and severity of vulnerabilities. Consequently, if security-related weaknesses can successfully be exploited by attackers, the functionality of critical infrastructure could be denied or malfunction. This might consequently threaten life or leak sensitive information. A toolkit to quantitatively express security is essential for security engineers in order to define security-enhancing measurements. For this purpose, security scoring frameworks, like the established Common Vulnerability Scoring System can be used. However, existing security scoring frameworks may not be able to handle the proposed challenges and characteristics of CPS. Therefore, in this work, we aim to elaborate a security scoring system that is tailored to the needs of CPS. In detail, we analyze security on a System-of-Systems level, while considering multiple attacks, as well as potential side effects to other security-related objects. The positive effects of integrated mitigation concepts should also be abbreviated by our proposed security score. Additionally, we generate the security score for interacting AUTOSAR platforms in a highly-connected Vehicle-to-everything (V2x) environment. We refer to this highly relevant use case scenario to underline the benefits of our proposed scoring framework and to prove its effectiveness in CPS.

In the federated learning system, parameter gradients are shared among participants and the central modulator, while the original data never leave their protected source domain. However, the gradient itself might carry enough information for precise inference of the original data. By reporting their parameter gradients to the central server, client datasets are exposed to inference attacks from adversaries. In this paper, we propose a quantitative metric based on mutual information for clients to evaluate the potential risk of information leakage in their gradients. Mutual information has received increasing attention in the machine learning and data mining community over the past few years. However, existing mutual information estimation methods cannot handle high-dimensional variables. In this paper, we propose a novel method to approximate the mutual information between the high-dimensional gradients and batched input data. Experimental results show that the proposed metric reliably reflect the extent of information leakage in federated learning. In addition, using the proposed metric, we investigate the influential factors of risk level. It is proven that, the risk of information leakage is related to the status of the task model, as well as the inherent data distribution.

The paper is devoted to the development and research of the redundancy cyber resiliency technique based on fast rerouting under security metric with the implementation of the basic schemes for network elements protection, namely node, link, path, and bandwidth. Within the model, the secure fast rerouting task is formulated as an optimization problem of nonlinear programming. The model is configured in order to calculate primary and backup paths that contain links with the minimum values of the probability of compromise that is achieved by using the appropriate weights in the objective function, the value of which is minimized. Numerical research has been conducted, results of which proved the proposed model efficiency and adequacy for the practical application.

The numerous attacks on ICS systems have made severe threats to critical infrastructure. Extensive studies have focussed on the risk assessment of discovering vulnerabilities. However, to identify Zero-day vulnerabilities is challenging because they are unknown to defenders. Here we sought to measure ICS system zero-day risk by building an enhanced attack graph for expected attack path exploiting zero-day vulnerability. In this study, we define the security metrics of Zero-day vulnerability for an ICS. Then we created a Zero-day attack graph to guide how to harden the system by measuring attack paths that exploiting zero-day vulnerabilities. Our studies identify the vulnerability assessment method on ICS systems considering Zero-day Vulnerability by zero-day attack graph. Together, our work is essential to ICS systems security. By assessing unknown vulnerability risk to close the imbalance between attackers and defenders.

The coupling of safety-relevant embedded- and cyber-space components to build Cyber-Physical Systems (CPS) extends the functionality and quality in many business domains, while also creating new ones. Prime examples like Internet of Things and Industry 4.0 enable new technologies and extend the service capabilities of physical entities by building a universe of connected devices. In addition to higher complexity, the coupling of these heterogeneous systems results in many new challenges, which should be addressed by engineers and administrators. Here, security represents a major challenge, which may be well addressed in cyber-space engineering, but less in embedded system or CPS design. Although model-based engineering provides significant benefits for system architects, like reducing complexity and automated analysis, as well as being considered as standard methodology in embedded systems design, the aspect of security may not have had a major role in traditional engineering concepts. Especially the characteristics of CPS, as well as the coupling of safety-relevant (physical) components with high-scalable entities of the cyber-space domain have an enormous impact on the overall level of security, based on the introduced side effects and uncertainties. Therefore, we aim to define a model-based security-engineering framework, which is tailored to the needs of CPS engineers. Hereby, we focus on the actual modeling process, the evaluation of security, as well as quantitatively expressing security of a deployed CPS. Overall and in contrast to other approaches, we shift the engineering concepts on a semantic level, which allows to address the proposed challenges in CPS in the most efficient way.

The importance of Cyber-Physical Systems (CPS) gains more and more weight in our daily business and private life. Although CPS build the backbone for major trends, like Industry 4.0 and connected vehicles, they also propose many new challenges. One major challenge can be found in achieving a high level of security within such highly connected environments, in which an unpredictable number of heterogeneous systems with often-distinctive characteristics interact with each other. In order to develop high-level security solutions, system designers must eventually know the current level of security of their specification. To this end, security metrics and scoring frameworks are essential, as they quantitatively express security of a given design or system. However, existing solutions may not be able to handle the proposed challenges of CPS, as they mainly focus on one particular system and one specific attack. Therefore, we aim to elaborate a security scoring mechanism, which can efficiently be used in CPS, while considering all essential information. We break down each system within the CPS into its core functional blocks and analyze a variety of attacks in terms of exploitability, scalability of attacks, as well as potential harm to targeted assets. With this approach, we get an overall assessment of security for the whole CPS, as it integrates the security-state of all interacting systems. This allows handling the presented complexity in CPS in a more efficient way, than existing solutions.

Over the years, a number of vulnerability scoring frameworks have been proposed to characterize the severity of known vulnerabilities in software-dependent systems. These frameworks provide security metrics to support decision-making in system development and security evaluation and assurance activities. When used in this context, it is imperative that these security metrics be sound, meaning that they can be consistently measured in a reproducible, objective, and unbiased fashion while providing contextually relevant, actionable information for decision makers. In this paper, we evaluate the soundness of the security metrics obtained via several vulnerability scoring frameworks. The evaluation is based on the Method for DesigningSound Security Metrics (MDSSM). We also present several recommendations to improve vulnerability scoring frameworks to yield more sound security metrics to support the development of secure software-dependent systems.

Implementations of Cyber-Physical Systems (CPS), like the Internet of Things, Smart Factories or Smart Grid gain more and more impact in their fields of application, as they extend the functionality and quality of the offered services significantly. However, the coupling of safety-critical embedded systems and services of the cyber-space domain introduce many new challenges for system engineers. Especially, the goal to achieve a high level of security throughout CPS presents a major challenge. However, it is necessary to develop and deploy secure CPS, as vulnerabilities and threats may lead to a non- or maliciously modified functionality of the CPS. This could ultimately cause harm to life of involved actors, or at least sensitive information can be leaked or lost. Therefore, it is essential that system engineers are aware of the level of security of the deployed CPS. For this purpose, security metrics and security evaluation frameworks can be utilized, as they are able to quantitatively express security, based on different measurements and rules. However, existing security scoring solutions may not be able to generate accurate security scores for CPS, as they insufficiently consider the typical CPS characteristics, like the communication of heterogeneous systems of physical- and cyber-space domain in an unpredictable manner. Therefore, we propose a security analysis framework, called Security Qualification Matrix (SQM). The SQM is capable to analyses multiple attacks on a System-of-Systems level simultaneously. With this approach, dependencies, potential side effects and the impact of mitigation concepts can quickly be identified and evaluated.

Network architecture design and verification has become increasingly complicated as a greater number of security considerations, implementations, and factors are included in the design process. In the design process, one must account for various costs of interwoven layers of security. Generally these costs are simplified for evaluation of risk to the network. The obvious implications of adding security are the need to account for the impacts of loss (risk) and accounting for the ensuing increased design costs. The considerations that are not traditionally examined are those of the adversary and the defender of a given system. Without accounting for the view point of the individuals interacting with a network architecture, one can not verify and select the most advantageous security implementation. This work presents a method for obtaining a security metric that takes into account not only the risk of the defender, but also the probability of an attack originating from the motivation of the adversary. We then move to a more meaningful metric based on a monetary unit that architects can use in choosing a best fit solution for a given network critical path design problem.

Nowadays, Information Technology is one of the important parts of human life and also of organizations. Organizations face problems such as IT problems. To solve these problems, they have to improve their security sections. Thus there is a need for security assessments within organizations to ensure security conditions. The use of security standards and general metric can be useful for measuring the safety of an organization; however, it should be noted that the general metric which are applied to businesses in general cannot be effective in this particular situation. Thus it's important to select metric standards for different businesses to improve both cost and organizational security. The selection of suitable security measures lies in the use of an efficient way to identify them. Due to the numerous complexities of these metric and the extent to which they are defined, in this paper that is based on comparative study and the benchmarking method, taxonomy for security measures is considered to be helpful for a business to choose metric tailored to their needs and conditions.

Security assurance is the confidence that a system meets its security requirements based on specific evidences that an assurance technique provide. The notion of measuring security is complex and tricky. Existing approaches either (1) consider one aspect of assurance, like security requirements fulfillment, or threat/vulnerability existence, or (2) do not consider the relevance of the different security requirements to the evaluated application context. Furthermore, they are mostly qualitative in nature and are heavily based on manual processing, which make them costly and time consuming. Therefore, they are not widely used and applied, especially by small and medium-sized enterprises (SME), which constitute the backbone of the Norwegian economy. In this paper, we propose a quantification method that aims at evaluating security assurance of systems by measuring (1) the level of confidence that the mechanisms fulfilling security requirements are present and (2) the vulnerabilities associated with possible security threats are absent. Additionally, an assurance evaluation process is proposed. Two case studies applying our method are presented. The case studies use our assurance method to evaluate the security level of two REST APIs developed by Statistics Norway, where one of the authors is employed. Analysis shows that the API with the most security mechanisms implemented got a slightly higher security assurance score. Security requirement relevance and vulnerability impact played a role in the overall scores.

Having an effective security level for Embedded System (ES), helps a reliable and stable operation of this system. In order to identify, if the current security level for a given ES is effective or not, we need a proactive evaluation for this security level. The evaluation of the security level for ESs is not straightforward process, things like the heterogeneity among the components of ES complicate this process. One of the productive approaches, which overcame the complexity of evaluation for Security, Privacy and Dependability (SPD) is the Multi Metrics (MM). As most of SPD evaluation approaches, the MM approach bases on the experts knowledge for the basic evaluation. Regardless of its advantages, experts evaluation has some drawbacks, which foster the need for less experts-dependent evaluation. In this paper, we propose a framework for security measurability as a part of security, privacy and dependability evaluation. The security evaluation based on Multi Metric (MM) approach as being an effective approach for evaluations, thus, we call it MM framework. The art of evaluation investigated within MM framework, based also on systematic storing and retrieving of experts knowledge. Using MM framework, the administrator of the ES could evaluate and enhance the S-level of their system, without being an expert in security.

Security Evaluation and Management (SEM) is considerably important process to protect the Embedded System (ES) from various kinds of security's exploits. In general, SEM's processes have some challenges, which limited its efficiency. Some of these challenges are system-based challenges like the hetero-geneity among system's components and system's size. Some other challenges are expert-based challenges like mis-evaluation possibility and experts non-continuous availability. Many of these challenges were addressed by the Multi Metric (MM) framework, which depends on experts' or subjective evaluation for basic evaluations. Despite of its productivity, subjective evaluation has some drawbacks (e.g. expert misevaluation) foster the need for considering objective evaluations in the MM framework. In addition, the MM framework is system centric framework, thus, by modelling complex and huge system using the MM framework a guide is needed indicating changes toward desirable security's requirements. This paper proposes extensions for the MM framework consider the usage of objective evaluations and work as guide for needed changes to satisfy desirable security requirements.

Security situational awareness is an essential building block in order to estimate security level of systems and to decide how to protect networked systems from cyber attacks. In this extended abstract we envision a model that combines results from security metrics to 3d network visualisation. The purpose is to apply security metrics to gather data from individual hosts. Simultaneously, the whole network is visualised in a 3d format, including network hosts and their connections. The proposed model makes it possible to offer enriched situational awareness for security administrators. This can be achieved by adding information pertaining to individual host into the network level 3d visualisation. Thus, administrator can see connected hosts and how the security of these hosts differs at one glance.