DAG-Based Attack and Defense Modeling: Don't Miss the Forest for the Attack Trees

This paper presents the current state of the art on attack and defense modeling approaches that are based on directed acyclic graphs (DAGs). DAGs allow for a hierarchical decomposition of complex scenarios into simple, easily understandable and quantifiable actions. Methods based on threat trees and Bayesian networks are two well-known approaches to security modeling. However there exist more than 30 DAG-based methodologies, each having different features and goals. The objective of this survey is to present a complete overview of graphical attack and defense modeling techniques based on DAGs. This consists of summarizing the existing methodologies, comparing their features and proposing a taxonomy of the described formalisms. This article also supports the selection of an adequate modeling technique depending on user requirements

A review of cyber security risk assessment methods for SCADA systems

This paper reviews the state of the art in cyber security risk assessment of Supervisory Control and Data Acquisition (SCADA) systems. We select and in-detail examine twenty-four risk assessment methods developed for or applied in the context of a SCADA system. We describe the essence of the methods and then analyse them in terms of aim; application domain; the stages of risk management addressed; key risk management concepts covered; impact measurement; sources of probabilistic data; evaluation and tool support. Based on the analysis, we suggest an intuitive scheme for the categorisation of cyber security risk assessment methods for SCADA systems. We also outline five research challenges facing the domain and point out the approaches that might be taken

Securing industrial control system environments: the missing piece

Cyberattacks on industrial control systems (ICSs) are no longer matters of anticipation. These systems are continually subject to malicious attacks without much resistance. Network breaches, data theft, denial of service, and command and control functions are examples of common attacks on ICSs. Despite available security solutions, safety, security, resilience, and performance require both private public sectors to step-up strategies to address increasing security concerns on ICSs. This paper reviews the ICS security risk landscape, including current security solution strategies in order to determine the gaps and limitations for effective mitigation. Notable issues point to a greater emphasis on technology security while discounting people and processes attributes. This is clearly incongruent with; emerging security risk trends, the biased security strategy of focusing more on supervisory control and data acquisition systems, and the emergence of more sector-specific solutions as against generic security solutions. Better solutions need to include approaches that follow similar patterns as the problem trend. These include security measures that are evolutionary by design in response to security risk dynamics. Solutions that recognize and include; people, process and technology security enhancement into asingle system, and addressing all three-entity vulnerabilities can provide a better solution for ICS environments

Improving resilience to cyber-attacks by analysing system output impacts and costs

Cyber-attacks cost businesses millions of dollars every year, a key component of which is the cost of business disruption from system downtime. As cyber-attacks cannot all be prevented, there is a need to consider the cyber resilience of systems, i.e. the ability to withstand cyber-attacks and recover from them. Previous works discussing system cyber resilience typically either offer generic high-level guidance on best practices, provide limited attack modelling, or apply to systems with special characteristics. There is a lack of an approach to system cyber resilience evaluation that is generally applicable yet provides a detailed consideration for the system-level impacts of cyber-attacks and defences. We propose a methodology for evaluating the effectiveness of actions intended to improve resilience to cyber-attacks, considering their impacts on system output performance, and monetary costs. It is intended for analysing attacks that can disrupt the system function, and involves modelling attack progression, system output production, response to attacks, and costs from cyber-attacks and defensive actions. Studies of three use cases demonstrate the implementation and usefulness of our methodology. First, in our redundancy planning study, we considered the effect of redundancy additions on mitigating the impacts of cyber-attacks on system output performance. We found that redundancy with diversity can be effective in increasing resilience, although the reduction in attack-related costs must be balanced against added maintenance costs. Second, our work on attack countermeasure selection shows that by considering system output impacts across the duration of an attack, one can find more cost-effective attack responses than without such considerations. Third, we propose an approach to mission viability analysis for multi-UAV deployments facing cyber-attacks, which can aid resource planning and determining if the mission can conclude successfully despite an attack. We provide different implementations of our model components, based on use case requirements.Open Acces

Security-Driven Software Evolution Using A Model Driven Approach

High security level must be guaranteed in applications in order to mitigate risks during the deployment of information systems in open network environments. However, a significant number of legacy systems remain in use which poses security risks to the enterprise’ assets due to the poor technologies used and lack of security concerns when they were in design. Software reengineering is a way out to improve their security levels in a systematic way. Model driven is an approach in which model as defined by its type directs the execution of the process. The aim of this research is to explore how model driven approach can facilitate the software reengineering driven by security demand. The research in this thesis involves the following three phases. Firstly, legacy system understanding is performed using reverse engineering techniques. Task of this phase is to reverse engineer legacy system into UML models, partition the legacy system into subsystems with the help of model slicing technique and detect existing security mechanisms to determine whether or not the provided security in the legacy system satisfies the user’s security objectives. Secondly, security requirements are elicited using risk analysis method. It is the process of analysing key aspects of the legacy systems in terms of security. A new risk assessment method, taking consideration of asset, threat and vulnerability, is proposed and used to elicit the security requirements which will generate the detailed security requirements in the specific format to direct the subsequent security enhancement. Finally, security enhancement for the system is performed using the proposed ontology based security pattern approach. It is the stage that security patterns derived from security expertise and fulfilling the elicited security requirements are selected and integrated in the legacy system models with the help of the proposed security ontology. The proposed approach is evaluated by the selected case study. Based on the analysis, conclusions are drawn and future research is discussed at the end of this thesis. The results show this thesis contributes an effective, reusable and suitable evolution approach for software security

Towards a standardised attack graph visual syntax

More research needs to focus on developing effective methods of aiding the understanding and perception of cyber-attacks. Attack modelling techniques (AMTs) - such as attack graphs, attack trees and fault trees, are popular methods of mathematically and visually representing the sequence of events that lead to a successful cyber-attack. Although useful in aiding cyber-attack perception, there is little empirical or comparative research which evaluates the effectiveness of these methods. Furthermore, there is no standardised attack graph visual syntax configuration, currently more than seventy-five self-nominated attack graph and twenty attack tree configurations have been described in the literature - each of which presents attributes such as preconditions and exploits in a different way. This research analyses methods of presenting cyber-attacks and reveals that attack graphs and attack trees are the dominant methods. The research proposes an attack graph visual syntax which is designed using evidence based principles. The proposed attack graph is compared with the fault tree - which is a standard method of representing events such as cyber-attacks. This comparison shows that the proposed attack graph visual syntax is more effective than the fault tree method at aiding cyber-attack perception and that the attack graph can be an effective tool for aiding cyber-attack perception - particularly in educational contexts. Although the proposed attack graph visual syntax is shown to be cognitively effective, this is no indication of practitioner acceptance. The research proceeds to identify a preferred attack graph visual syntax from a range of visual syntaxes - one of which is the proposed attack graph visual syntax. The method used to perform the comparison is conjoint analysis which is innovative for this field. The results of the second study reveal that the proposed attack graph visual syntax is one of the preferred configurations. This attack graph has the following attributes. The flow of events is represented top-down, preconditions are represented as rectangles, and exploits are represented as ellipses. The key contribution of this research is the development of an attack graph visual syntax which is effective in aiding the understanding of cyber-attacks particularly in educational contexts. The proposed method is a significant step towards standardising the attack graph visual syntax

Evaluation of Efficiency of Cybersecurity

Uurimistöö eesmärgiks on uurida, kuidas tõhus küberjulgeolek on olnud edukas. Uurimistöö kasutab parima võimaliku tulemuse saamiseks mitmesuguseid uurimismeetodeid ja kirjanduse ülevaade on süstemaatiline. Kuid uurimistöö järeldus on see, et uuring ei suuda kinnitada või tagasi lükata peamist töö hüpoteesi. Uuring ei õnnestunud, sest puuduvad korralikud teooriad, mis näitavad ohutuse ja küberjulgeoleku nähtusi ning puuduvad head näitajad, mis annaksid küberohutuse tõhususe kohta kehtivaid ja ratsionaalseid tulemusi, kui hästi on küberkuritegevuse abil õnnestunud küberkuritegevuse tõhusaks võitmiseks ja küberkuritegude tõhusaks vähendamiseks. Seepärast on küberjulgeoleku teadusteooria ja julgeoleku teadusteooria vähearenenud 2018. aastal. Uuringud on teinud küberjulgeoleku ja turvalisuse arendamise põhilisi avastusi. Edasiste põhiuuringute suund on luua üldine turbeteooria, mis kirjeldab ohtlike muutujate ohtlike muutujate kavatsust, ressursse, pädevust ja edusamme ohtlike muutujate ja aksioomide puhul, kus ohtlike muutujate mõõtmisel saab teha selle sisse loodetavas ja teooria kirjeldab, millised on tõhusad meetmed, et vältida ja leevendada ning millised ei ole ja lõpuks kehtestada nõuetekohased mõõdikud, et mõõta turvalisuse ja küberjulgeoleku tõhusust loodetavus ja kehtivusega.The purpose of the thesis is to research how effectively cybersecurity has succeeded on its mission. The thesis used multiple research methods to get best possible answer and the literature review has been systematic. However, the conclusion of the research was that the study is unable to either confirm or reject the main working hypothesis. The study is unable to do it because of the lack of proper theories to describe what are the phenomena in secu-rity and cybersecurity and the lack of proper metrics to give valid and sound conclusion about the effective of cybersecurity and how well have cybersecurity succeed on its mis-sion to effectively prevent and mitigate cybercrime. Therefore, the science of security and science of cybersecurity are underdeveloped in 2018. The research has made basic discov-eries of development of cybersecurity and security. A direction of further basic research is to establish a general theory of security which describes threat variables, threat variables intention, resources, competence and progress of the threat variables and axioms where measurement of threat variables can be made with reliability and the theory would describe which are effective measures to prevent and mitigate and which are not and finally, estab-lish proper metrics to measure efficiency of security and cybersecurity with reliability and validity

Partially-Observable Security Games for Automating Attack-Defense Analysis

Network systems often contain vulnerabilities that remain unfixed in a network for various reasons, such as the lack of a patch or knowledge to fix them. With the presence of such residual vulnerabilities, the network administrator should properly react to the malicious activities or proactively prevent them, by applying suitable countermeasures that minimize the likelihood of an attack by the attacker. In this paper, we propose a stochastic game-theoretic approach for analyzing network security and synthesizing defense strategies to protect a network. To support analysis under partial observation, where some of the attacker's activities are unobservable or undetectable by the defender, we construct a one-sided partially observable security game and transform it into a perfect game for further analysis. We prove that this transformation is sound for a sub-class of security games and a subset of properties specified in the logic rPATL. We implement a prototype that fully automates our approach, and evaluate it by conducting experiments on a real-life network