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Ghorbal, Khalil, Jeannin, Jean-Baptiste, Zawadzki, Erik, Platzer, Andre, Gordon, Geoffrey, Capell, Peter.  2014.   Hybrid theorem proving of aerospace systems: Applications and challenges. Journal of Aerospace Information Systems . 11(10)

Complex software systems are becoming increasingly prevalent in aerospace applications: in particular, to
accomplish critical tasks. Ensuring the safety of these systems is crucial, as they can have subtly different behaviors
under slight variations in operating conditions. This paper advocates the use of formal verification techniques and in
particular theorem proving for hybrid software-intensive systems as a well-founded complementary approach to the
classical aerospace verification and validation techniques, such as testing or simulation. As an illustration of these
techniques, a novel lateral midair collision-avoidance maneuver is studied in an ideal setting, without accounting for
the uncertainties of the physical reality. The challenges that naturally arise when applying such technology to
industrial-scale applications is then detailed, and proposals are given on how to address these issues.

Ghita Mezzour.  2015.  Assessing the Global Cyber and Biological Threat. Electrical and Computer Engineering Department and Institute for Software Research. Doctor of Philosophy

In today’s inter-connected world, threats from anywhere in the world can have serious global repercussions. In particular, two types of threats have a global impact: 1) cyber crime and 2) cyber and biological weapons. If a country’s environment is conducive to cyber criminal activities, cyber criminals will use that country as a basis to attack end-users around the world. Cyber weapons and biological weapons can now allow a small actor to inflict major damage on a major military power. If cyber and biological weapons are used in combination, the damage can be amplified significantly. Given that the cyber and biological threat is global, it is important to identify countries that pose the greatest threat and design action plans to reduce the threat from these countries. However, prior work on cyber crime lacks empirical substantiation for reasons why some countries’ environments are conducive to cyber crime. Prior work on cyber and biological weapon capabilities mainly consists of case studies which only focus on select countries and thus are not generalizeable. To sum up, assessing the global cyber and biological threat currently lacks a systematic empirical approach. In this thesis, I take an empirical and systematic approach towards assessing the global cyber and biological threat. The first part of the thesis focuses on cyber crime. I examine international variation in cyber crime infrastructure hosting and cyber crime exposure. I also empirically test hypotheses about factors behind such variation. In that work, I use Symantec’s telemetry data, collected from 10 million Symantec customer computers worldwide and accessed through the Symantec’s Worldwide Intelligence Network Environment (WINE). I find that addressing corruption in Eastern Europe or computer piracy in Sub-Saharan Africa has the potential to reduce the global cyber crime. The second part of the thesis focuses on cyber and biological weapon capabilities. I develop two computational methodologies: one to assess countries’ biological capabilities and one to assess countries’ cyber capabilities. The methodologies examine all countries in the world and can be used by non-experts that only have access to publicly available data. I validate the biological weapon assessment methodology by comparing the methodology’s assessment to historical data. This work has the potential to proactively reduce the global cyber and biological weapon threat.

Ghita Mezzour, Kathleen Carley, L. Richard Carley.  2015.  An empirical study of global malware encounters. HotSoS '15 Proceedings of the 2015 Symposium and Bootcamp on the Science of Security.

The number of trojans, worms, and viruses that computers encounter varies greatly across countries. Empirically identifying factors behind such variation can provide a scientific empirical basis to policy actions to reduce malware encounters in the most affected countries. However, our understanding of these factors is currently mainly based on expert opinions, not empirical evidence.

In this paper, we empirically test alternative hypotheses about factors behind international variation in the number of trojan, worm, and virus encounters. We use the Symantec Anti-Virus (AV) telemetry data collected from more than 10 million Symantec customer computers worldwide that we accessed through the Symantec Worldwide Intelligence Environment (WINE) platform. We use regression analysis to test for the effect of computing and monetary resources, web browsing behavior, computer piracy, cyber security expertise, and international relations on international variation in malware encounters.

We find that trojans, worms, and viruses are most prevalent in Sub-Saharan African countries. Many Asian countries also encounter substantial quantities of malware. Our regression analysis reveals that the main factor that explains high malware exposure of these countries is a widespread computer piracy especially when combined with poverty. Our regression analysis also reveals that, surprisingly, web browsing behavior, cyber security expertise, and international relations have no significant effect.

Ghita Mezzour, L. Richard Carley, Kathleen Carley.  2014.  Global Mapping of Cyber Attacks.

Identifying factors behind countries’ weakness to cyber-attacks is an important step towards addressing these weaknesses at the root level.  For example, identifying factors why some countries become cyber- crime safe heavens can inform policy actions about how to reduce the attractiveness of these countries to cyber-criminals.  Currently, however, identifying these factors is mostly based on expert opinions and speculations.

In this work, we perform an empirical study to statistically test the validity of these opinions and specu- lations.  In our analysis, we use Symantec’s World Intelligence Network Environment (WINE) Intrusion Prevention System (IPS) telemetry data which contain attack reports from more than 10 million customer computers worldwide.  We use regression analysis to test for the relevance of multiple factors including monetary and computing resources, cyber-security research and institutions, and corruption.

Our analysis confirms some hypotheses and disproves others. We find that many countries in Eastern Europe extensively host attacking computers because of a combination of good computing infrastructure and high corruption rate.  We also find that web attacks and fake applications are most prevalent in rich countries because attacks on these countries are more lucrative. Finally, we find that computers in Africa launch the lowest rates of cyber-attacks. This is surprising given the bad cyber reputation of some African countries such as Nigeria. Our research has many policy implications.

Gabriel Moreno, Javier Camara, David Garlan, Bradley Schmerl.  2015.  Proactive Self-Adaptation under Uncertainty: a Probabilistic Model Checking Approach. ESEC/FSE 2015 Proceedings of the 2015 10th Joint Meeting on Foundations of Software Engineering.

Self-adaptive systems tend to be reactive and myopic, adapting in response to changes without anticipating what the subsequent adaptation needs will be. Adapting reactively can result in inefficiencies due to the system performing a suboptimal sequence of adaptations. Furthermore, when adaptations have latency, and take some time to produce their effect, they have to be started with sufficient lead time so that they complete by the time their effect is needed. Proactive latency-aware adaptation addresses these issues by making adaptation decisions with a look-ahead horizon and taking adaptation latency into account. In this paper we present an approach for proactive latency-aware adaptation under uncertainty that uses probabilistic model checking for adaptation decisions. The key idea is to use a formal model of the adaptive system in which the adaptation decision is left underspecified through nondeterminism, and have the model checker resolve the nondeterministic choices so that the accumulated utility over the horizon is maximized. The adaptation decision is optimal over the horizon, and takes into account the inherent uncertainty of the environment predictions needed for looking ahead. Our results show that the decision based on a look-ahead horizon, and the factoring of both tactic latency and environment uncertainty, considerably improve the effectiveness of adaptation decisions.

Gabriel Ferreira, Christian Kästner, Jurgen Pfeffer, Sven Apel.  2015.  Characterizing complexity of highly-configurable systems with variational call graphs: analyzing configuration options interactions complexity in function calls. HotSoS '15 Proceedings of the 2015 Symposium and Bootcamp on the Science of Security.

Security has consistently been the focus of attention in many highly-configurable software systems. Several vulnerabilities on widely-used systems, such as the Linux kernel and OpenSSL, are reported every day in the National Vulnerability Database (NVD). The configurability of these systems enables the rapid generation of customized products, but also creates security challenges in the development and maintenance processes. For instance, interactions caused by configurations may create serious security threats and make generated products more susceptible to attacks [6], but the causes of these problems may be harder to detect because they occur only in specific configurations.

Gabriel Ferreira, Momin Malik, Christian Kästner, Jurgen Pfeffer, Sven Apel.  2016.  Do #ifdefs influence the occurrence of vulnerabilities? an empirical study of the linux kernel SPLC '16 Proceedings of the 20th International Systems and Software Product Line Conference. :65-73.

Preprocessors support the diversification of software products with #ifdefs, but also require additional effort from developers to maintain and understand variable code. We conjecture that #ifdefs cause developers to produce more vulnerable code because they are required to reason about multiple features simultaneously and maintain complex mental models of dependencies of configurable code.

We extracted a variational call graph across all configurations of the Linux kernel, and used configuration complexity metrics to compare vulnerable and non-vulnerable functions considering their vulnerability history. Our goal was to learn about whether we can observe a measurable influence of configuration complexity on the occurrence of vulnerabilities.

Our results suggest, among others, that vulnerable functions have higher variability than non-vulnerable ones and are also constrained by fewer configuration options. This suggests that developers are inclined to notice functions appear in frequently-compiled product variants. We aim to raise developers' awareness to address variability more systematically, since configuration complexity is an important, but often ignored aspect of software product lines.

Gabriel Ferreira.  2017.  Software certification in practice: how are standards being applied? ICSE-C '17 Proceedings of the 39th International Conference on Software Engineering Companion.

Certification schemes exist to regulate software systems and prevent them from being deployed before they are judged fit to use. However, practitioners are often unsatisfied with the efficiency of certification standards and processes. In this study, we analyzed two certification standards, Common Criteria and DO-178C, and collected insights from literature and from interviews with subject-matter experts to identify concepts affecting the efficiency of certification processes. Our results show that evaluation time, reusability of evaluation artifacts, and composition of systems and certified artifacts are barriers to achieve efficient certification.