Expressive Policy Analysis with Enhanced System Dynamicity

Despite several research studies, the effective analysis of policy based systems remains a significant challenge. Policy analysis should at least (i) be expressive (ii) take account of obligations and authorizations, (iii) include a dynamic system model, and (iv) give useful diagnostic information. We present a logic-based policy analysis framework which satisfies these requirements, showing how many significant policy-related properties can be analysed, and we give details of a prototype implementation. Copyright 2009 ACM

Improving the Policy Specification for Practical Access Control Systems

Access control systems play a crucial role in protecting the security of information systems by ensuring that only authorized users are granted access to sensitive resources, and the protection is only as good as the access control policies. For enabling a security administrator to express her desired policy conveniently, it is paramount that a policy specification is expressive, comprehensible, and free of inconsistencies. In this dissertation, we study the policy specifications for three practical access control systems (i.e., obligation systems, firewalls, and Security-Enhanced Linux in Android) and improve their expressiveness, comprehensibility, and consistency. First, we improve the expressiveness of obligation policies for handling different types of obligations. We propose a language for specifying obligations as well as an architecture for handling access control policies with these obligations, by extending XACML (i.e., the de facto standard for specifying access control policies). We also implement our design into a prototype system named ExtXACML to handle various obligations. Second, we improve the comprehensibility of firewall policies enabling administrators to better understand and manage the policies. We introduce the tri-modularized design of firewall policies for elevating them from monolithic to modular. To support legacy firewall policies, we also define a five-step process and present algorithms for converting them into their modularized form. Finally, we improve the consistency of Security-Enhanced Linux in Android (SEAndroid) policies for reducing the attack surface in Android systems. We propose a systematic approach as well as a semiautomatic tool for uncovering three classes of policy misconfigurations. We also analyze SEAndroid policies from four Android versions and seven Android phone vendors, and in all of them we observe examples of potential policy misconfigurations

Context-based confidentiality analysis in dynamic Industry 4.0 scenarios

In Industry 4.0 environments highly dynamic and flexible access control strategies are needed. State of the art strategies are often not included in the modelling process but must be considered afterwards. This makes it very difficult to analyse the security properties of a system. In the framework of the Trust 4.0 project the confidentiality analysis tries to solve this problem using a context-based approach. Thus, there is a security model named context metamodel. Another important problem is that the transformation of an instance of a security model to a wide-spread access control standard is often not possible. This is also the case for the context metamodel. Moreover, another transformation which is very interesting to consider is one to an ensemble based component system which is also presented in the Trust 4.0 project. This thesis introduces an extension to the beforementioned context metamodel in order to add more extensibility to it. Furthermore, the thesis deals with the creation of a concept and an implementation of the transformations mentioned above. For that purpose, at first, the transformation to the attribute-based access control standard XACML is considered. Thereafter, the transformation from XACML to an ensemble based component system is covered. The evaluation indicated that the model can be used for use cases in Industry 4.0 scenarios. Moreover, it also indicated the transformations produce adequately accurate access policies. Furthermore, the scalability evaluation indicated linear runtime behaviour of the implementations of both transformations for respectively higher number of input contexts or XACML rules

Clustering and recommendation techniques for access control policy management

Managing access control policies can be a daunting process, given the frequent policy decisions that need to be made, and the potentially large number of policy rules involved. Policy management includes, but is not limited to: policy optimization, configuration, and analysis. Such tasks require a deep understanding of the policy and its building compo- nents, especially in scenarios where it frequently changes and needs to adapt to different environments. Assisting both administrators and users in performing these tasks is impor- tant in avoiding policy misconfigurations and ill-informed policy decisions. We investigate a number of clustering and recommendation techniques, and implement a set of tools that assist administrators and users in managing their policies. First, we propose and imple- ment an optimization technique, based on policy clustering and adaptable rule ranking, to achieve optimal request evaluation performance. Second, we implement a policy analysis framework that simplifies and visualizes analysis results, based on a hierarchical cluster- ing algorithm. The framework utilizes a similarity-based model that provides a basis of risk analysis on newly introduced policy rules. In addition to administrators, we focus on regular individuals whom nowadays manage their own access control polices on a regular basis. Users are making frequent policy decisions, especially with the increasing popular- ity of social network sites, such as Facebook and Twitter. For example, users are required to allow/deny access to their private data on social sites each time they install a 3rd party application. To make matters worse, 3rd party access requests are mostly uncustomizable by the user. We propose a framework that allows users to customize their policy decisions on social sites, and provides a set of recommendations that assist users in making well- informed decisions. Finally, as the browser has become the main medium for the users online presence, we investigate the access control models for 3rd party browser extensions. Even though, extensions enrich the browsing experience of users, they could potentially represent a threat to their privacy. We propose and implement a framework that 1) monitors 3rd party extension accesses, 2) provides fine-grained permission controls, and 3) Provides detailed permission information to users in effort to increase their privacy aware- ness. To evaluate the framework we conducted a within-subjects user study and found the framework to effectively increase user awareness of requested permissions

Steps towards adaptive situation and context-aware access: a contribution to the extension of access control mechanisms within pervasive information systems

L'évolution des systèmes pervasives a ouvert de nouveaux horizons aux systèmes d'information classiques qui ont intégré des nouvelles technologies et des services qui assurent la transparence d'accès aux resources d'information à n'importe quand, n'importe où et n'importe comment. En même temps, cette évolution a relevé des nouveaux défis à la sécurité de données et à la modélisation du contrôle d'accès. Afin de confronter ces challenges, differents travaux de recherche se sont dirigés vers l'extension des modèles de contrôles d'accès (en particulier le modèle RBAC) afin de prendre en compte la sensibilité au contexte dans le processus de prise de décision. Mais la liaison d'une décision d'accès aux contraintes contextuelles dynamiques d'un utilisateur mobile va non seulement ajouter plus de complexité au processus de prise de décision mais pourra aussi augmenter les possibilités de refus d'accès. Sachant que l'accessibilité est un élément clé dans les systèmes pervasifs et prenant en compte l'importance d'assurer l'accéssibilité en situations du temps réel, nombreux travaux de recherche ont proposé d'appliquer des mécanismes flexibles de contrôle d'accès avec des solutions parfois extrêmes qui depassent les frontières de sécurité telle que l'option de "Bris-de-Glace". Dans cette thèse, nous introduisons une solution modérée qui se positionne entre la rigidité des modèles de contrôle d'accès et la flexibilité qui expose des risques appliquées pendant des situations du temps réel. Notre contribution comprend deux volets : au niveau de conception, nous proposons PS-RBAC - un modèle RBAC sensible au contexte et à la situation. Le modèle réalise des attributions des permissions adaptatives et de solution de rechange à base de prise de décision basée sur la similarité face à une situation importanteÀ la phase d'exécution, nous introduisons PSQRS - un système de réécriture des requêtes sensible au contexte et à la situation et qui confronte les refus d'accès en reformulant la requête XACML de l'utilisateur et en lui proposant une liste des resources alternatives similaires qu'il peut accéder. L'objectif est de fournir un niveau de sécurité adaptative qui répond aux besoins de l'utilisateur tout en prenant en compte son rôle, ses contraintes contextuelles (localisation, réseau, dispositif, etc.) et sa situation. Notre proposition a été validé dans trois domaines d'application qui sont riches des contextes pervasifs et des scénarii du temps réel: (i) les Équipes Mobiles Gériatriques, (ii) les systèmes avioniques et (iii) les systèmes de vidéo surveillance.The evolution of pervasive computing has opened new horizons to classical information systems by integrating new technologies and services that enable seamless access to information sources at anytime, anyhow and anywhere. Meanwhile this evolution has opened new threats to information security and new challenges to access control modeling. In order to meet these challenges, many research works went towards extending traditional access control models (especially the RBAC model) in order to add context awareness within the decision-making process. Meanwhile, tying access decisions to the dynamic contextual constraints of mobile users would not only add more complexity to decision-making but could also increase the possibilities of access denial. Knowing that accessibility is a key feature for pervasive systems and taking into account the importance of providing access within real-time situations, many research works have proposed applying flexible access control mechanisms with sometimes extreme solutions that depass security boundaries such as the Break-Glass option. In this thesis, we introduce a moderate solution that stands between the rigidity of access control models and the riskful flexibility applied during real-time situations. Our contribution is twofold: on the design phase, we propose PS-RBAC - a Pervasive Situation-aware RBAC model that realizes adaptive permission assignments and alternative-based decision-making based on similarity when facing an important situation. On the implementation phase, we introduce PSQRS - a Pervasive Situation-aware Query Rewriting System architecture that confronts access denials by reformulating the user's XACML access request and proposing to him a list of alternative similar solutions that he can access. The objective is to provide a level of adaptive security that would meet the user needs while taking into consideration his role, contextual constraints (location, network, device, etc.) and his situation. Our proposal has been validated in three application domains that are rich in pervasive contexts and real-time scenarios: (i) Mobile Geriatric Teams, (ii) Avionic Systems and (iii) Video Surveillance Systems

Developing focused auditing tools: A practical framework for creating formalized multi-level security policy specifications

The purpose of this study is that formalized policy specifications and focused penetration testing are needed to effectively audit any information system. Designing and maintaining the security system information is the primary duty of the cyber security professional. In today\u27s world, nearly all government agencies manage some form of financial, defense, national security, and/or privacy information security policies. It is also necessary in this environment that agencies are accountable for auditing the security systems that protect this information

Traduciendo OCL como lenguaje de consultas y restricciones

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Informática, Departamento de Sistemas Informáticos y Computación, leída el 30-06-2017Esta tesis doctoral debe gran parte de su motivación inicial y enfoque final a la discusión muy animada y perspicaz que tuvo lugar durante el seminario “Automated Reasoning on Conceptual Schemas” en Dagstuhl (19-24 Mayo, 2013) [18], en el cual tuvimos la fortuna de participar.Incluso antes de asistir al seminario, sobre la base de nuestra propia experiencia aplicando la metodología de desarrollo dirigida por modelos en el proyecto Action GUI [1],ya estábamos convencidos de la veracidad y la importancia de tres declaraciones claves contenidas en la presentación del mismo, que resumen muy bien las motivaciones finales de esta tesis:“La calidad de un sistema de información se determina en gran medida a principios del ciclo de desarrollo, es decir, durante la especificación de los requisitos y el modelado conceptual, ya que los errores introducidos en estas etapas suelen ser mucho más costosos de corregir que los errores cometidos durante el diseño o la implementación.”“Por lo tanto, es deseable prevenir, detectar y corregir errores tan pronto como sea posible en el proceso de desarrollo evaluando la corrección de los esquemas conceptuales construidos.”“La alta expresividad de los esquemas conceptuales requiere adoptar técnicas de razonamiento automatizadas para apoyar al diseñador en esta importante tarea.”...This doctoral dissertation owes a great deal of its initial motivation and final focusto the very lively and insightful discussion that took place during the Dagstuhl Seminar“Automated Reasoning on Conceptual Schemas” (19-24 May, 2013) [18], which we havethe fortune to participate in.Even before attending the seminar, based on our own experience applying the modeldrivendevelopment methodology within the ActionGUI project [1], we were already convincedof the truthfulness and importance of three key statements contained in the seminar’spresentation, which summarize very well this dissertation’s ultimate motivations:“The quality of an information system is largely determined early in the developmentcycle, i.e., during requirements specification and conceptual modeling, since errorsintroduced at these stages are usually much more expensive to correct than errorsmade during design or implementation.”“Thus, it is desirable to prevent, detect, and correct errors as early as possible in thedevelopment process by assessing the correctness of the conceptual schemas built.”“The high expressivity of conceptual schemas requires to adopt automated reasoningtechniques to support the designer in this important task.”..Depto. de Sistemas Informáticos y ComputaciónFac. de InformáticaTRUEunpu