Role-Based Access Control Administration of Security Policies and Policy Conflict Resolution in Distributed Systems

Security models using access control policies have over the years improved from Role-based access control (RBAC) to newer models which have added some features like support for distributed systems and solving problems in older security policy models such as identifying policy conflicts. Access control policies based on hierarchical roles provide more flexibility in controlling system resources for users. The policies allow for granularity when extended to have both allow and deny permissions as well as weighted priority attribute for the rules in the policies. Such flexibility allows administrators to succinctly specify access for their system resources but also prone to conflict. This study found that conflicts in access control policies were still a problem even in recent literature. There have been successful attempts at using algorithms to identify the conflicts. However, the conflicts were only identified but not resolved or averted and system administrators still had to resolve the policy conflicts manually. This study proposed a weighted attribute administration model (WAAM) containing values that feed the calculation of a weighted priority attribute. The values are tied to the user, hierarchical role, and secured objects in a security model to ease their administration and are included in the expression of the access control policy. This study also suggested a weighted attribute algorithm (WAA) using these values to resolve any conflicts in the access control policies. The proposed solution was demonstrated in a simulation that combined the WAAM and WAA. The simulation\u27s database used WAAM and had data records for access control policies, some of which had conflicts. The simulation then showed that WAA could both identify and resolve access control policy (ACP) conflicts while providing results in sub-second time. The WAA is extensible so implementing systems can extend WAA to meet specialized needs. This study shows that ACP conflicts can be identified and resolved during authorization of a user into a system

Uma abordagem de recomendação sensível ao contexto para apoio a autenticação implícita em ambientes móveis e pervasivos baseado em conhecimento comportamental do usuário

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-graduação em Engenharia e Gestão do Conhecimento, Florianópolis, 2013Muitas empresas começam a adaptar-se às tecnologias e aos dispositivos móveis, incorporando no seu cotidiano, os benefícios proporcionados pela mobilidade e a possibilidade do Trabalho Móvel. Os serviços acessados pelos dispositivos móveis, geralmente, utilizam processos de autenticação baseado em credenciais (por exemplo, senha), que se mostram vulneráveis e inadequados. Logo, abordagens alternativas de autenticação devem considerar as características ambientais (consciência do contexto), restrições dos dispositivos, privacidade das informações armazenadas e informações provenientes dos muitos sensores que estão presentes no espaço pervasivo. Esta pesquisa propõe uma abordagem de recomendação baseado em comportamento do usuário para autenticação implícita no espaço pervasivo em que este se encontra. O comportamento dos usuários é modelado através de um conjunto de características de contexto e de atividades, que os usuários executam. Os usuários possuem atividades diárias, semanais e mensais que formam um conjunto de hábitos executados regularmente. O monitoramento destes hábitos permite indicar se um usuário legítimo está executando as suas atividades ou se outra pessoa está acessando sem autorização os serviços e informações do dispositivo móvel. Portanto, a combinação das características contextuais e as atividades (hábitos) auxiliam o processo de reconhecimento e certificação do usuário. Os processos de filtragem do sistema de recomendação, permitem a adição de novos filtros que calculam a similaridade dos comportamentos dos usuários. Os filtros são classificados em: i) filtros locais, que trabalham com algoritmos de baixa complexidade devido aos recursos computacionais limitados dos dispositivos móveis, e ii) filtros remotos, que trabalham com algoritmos mais complexos e podem executar ferramentas estatísticas nos servidores de autenticação. Os resultados experimentais indicam com sucesso: i) um mecanismo mais dinâmico (adaptável às atividades executadas pelo usuário) e autonômico para autenticação de usuários em um ambiente móvel e pervasivo, e ii) uma eficiência significativa na detecção de anomalias de autenticação através da utilização de modelos de similaridade e permutação espaço-temporal Abstratct: Many companies are beginning to adapt to technologies and mobiledevices, incorporating in their daily lives, the benefits provided by the mobilityand the possibility of Labour Mobile. The services accessed by mobiledevices typically use authentication processes based on credentials (e.g., password),that are vulnerable and inadequate. Therefore, alternative approachesto authentication should consider the environmental characteristics (contextawareness),constraints of devices, privacy of information stored and informationfrom many sensors that are present in pervasive space. This researchpropose a recommendation approach based on user behavior for implicitauthentication in pervasive space in which it is located. The user behavioris modeled by a set of characteristics of context and activities that users perform.Users have daily , weekly and monthly activities forming a set of habits,which are performed regularly. The monitoring of these habits is usedto indicate if a legitimate user is running their activities or if someone elseis accessing without authorization services and information of the mobile device.Therefore, the combination of contextual characteristics and activities(habits) assist the process of recognition and certification of the user. Theprocess of filtering recommendation system , allow the addition of new filtersthat compute the similarity of users? behaviors. Filters are classified into:i) local filters that work with low-complexity algorithms due to the limitedcomputing resources of mobile devices, and ii) filters remote working withmore complex algorithms and statistical tools can perform the authenticationservers. The experimental results indicate successfully: i) a mechanism moredynamic (adaptable to the activities performed by the user) and autonomicfor authentication users in a mobile and pervasive environment, and ii) anefficiency in the detection of anomalies authentication by using models ofsimilarity and spatio-temporal permutation

Context Sensitive Access Control Model TI for Business Processes

Kontrola pristupa odnosno autorizacija, u širem smislu, razmatra na koji način korisnici mogu pristupiti resursima računarskog sistema i na koji način ih koristiti. Ova disertacija se bavi problemima kontrole pristupa u poslovnim sistemima. Tema disertacije je formalna specifkacija modela kontekstno zavisne kontrole pristupa u poslovnim sistemima koji je baziran na RBAC modelu kontrole pristupa. Uvođenjem kontekstno zavisne kontrole pristupa omogućeno je defnisanje složenijih prava pristupa koje u postojećim modelima kontrole pristupa za poslovne sisteme nije bilo moguće realizovati ili bi njihova realizacija bila komplikovana. Dati model primenljiv je u različitim poslovnim sistemima, a podržava defnisanje prava pristupa kako za jednostavne tako i za slo·zene poslovne tokove. Sistem je verifkovan na dva realna poslovna procesa pomoću razvijenog prototipa. Prikazana prototipska implementacija koja ispunjava ciljeve u pogledu funkcionalnosti postavljene pred sistem predstavlja potvrdu praktične vrednosti predloženog modela.Access control is concerned with the way in which users can access to resources in the computer system. This dissertation focuses on problems of access control for business processes. The subject of the dissertation is a formal specification of the RBAC-based context sensitive access control model for business processes. By using a context-sensitive access control it is possible to define more complex access control policies whose implementation in existing access control models for business processes is not possible or is very complicated. The given model is applicable in diferent business systems, and supports the definition of access control policies for both simple and complex business processes. The model's prototype is verified by two case studies on real business processes. The presented prototype implementation represents a proof of the proposed model's practical value

Erfassung und Behandlung von Positionsfehlern in standortbasierter Autorisierung

Durch die immer größeren technischen Möglichkeiten mobiler Endgeräte sind die Voraussetzungen erfüllt, um diese zum mobilen Arbeiten oder zur Steuerung von industriellen Fertigungsprozessen einzusetzen. Aus Gründen der Informations- und Betriebssicherheit, sowie zur Umsetzung funktionaler Anforderungen, ist es aber vielfach erforderlich, die Verfügbarkeit von entsprechenden Zugriffsrechten auf Nutzer innerhalb autorisierter Zonen zu begrenzen. So kann z.B. das Auslesen kritischer Daten auf individuelle Büros oder die mobile Steuerung von Maschinen auf passende Orte innerhalb einer Fabrikhalle beschränkt werden. Dazu muss die Position des Nutzers ermittelt werden. Im realen Einsatz können Positionsschätzungen jedoch mit Fehlern in der Größe von autorisierten Zonen auftreten. Derzeit existieren noch keine Lösungen, welche diese Fehler in Autorisierungsentscheidungen berücksichtigen, um einhergehenden Schaden aus Falschentscheidungen zu minimieren. Ferner existieren derzeit keine Verfahren, um die Güteeigenschaften solcher Ortsbeschränkungen vor deren Ausbringung zu analysieren und zu entscheiden, ob ein gegebenes Positionierungssystem aufgrund der Größe seiner Positionsfehler geeignet ist. In der vorliegenden Arbeit werden deshalb Lösungen zur Erfassung und Behandlung solcher Positionsfehler im Umfeld der standortbasierten Autorisierung vorgestellt. Hierzu wird zunächst ein Schätzverfahren für Positionsfehler in musterbasierten Positionierungsverfahren eingeführt, das aus den Charakteristika der durchgeführten Messungen eine Verteilung für den Standort des Nutzers ableitet. Um hieraus effizient die Aufenthaltswahrscheinlichkeit innerhalb einer autorisierten Zone zu bestimmen, wird ein Algorithmus vorgestellt, der basierend auf Vorberechnungen eine erhebliche Verbesserung der Laufzeit gegenüber der direkten Berechnung erlaubt. Erstmals wird eine umfassende Gegenüberstellung von existierenden standortbasierten Autorisierungsstrategien auf Basis der Entscheidungstheorie vorgestellt. Mit der risikobasierten Autorisierungsstrategie wird eine neue, aus entscheidungstheoretischer Sicht optimale Methodik eingeführt. Es werden Ansätze zur Erweiterung klassischer Zugriffskontrollmodelle durch Ortsbeschränkungen vorgestellt, welche bei ihrer Durchsetzung die Möglichkeit von Positionsfehlern und die Konsequenzen von Falschentscheidungen berücksichtigen. Zur Spezifikation autorisierter Zonen werden Eigenschaftsmodelle eingeführt, die, im Gegensatz zu herkömmlichen Polygonen, für jeden Ort die Wahrscheinlichkeit modellieren, dort eine geforderte Eigenschaft zu beobachten. Es werden ferner Methoden vorgestellt, um den Einfluss von Messausreißern auf Autorisierungsentscheidungen zu reduzieren. Ferner werden Analyseverfahren eingeführt, die für ein gegebenes Szenario eine qualitative und quantitative Bewertung der Eignung von Positionierungssystemen erlauben. Die quantitative Bewertung basiert auf dem entwickelten Konzept der Autorisierungsmodelle. Diese geben für jeden Standort die Wahrscheinlichkeit an, dort eine Positionsschätzung zu erhalten, die zur Autorisierung führt. Die qualitative Bewertung bietet erstmals ein binäres Kriterium, um für ein gegebenes Szenario eine konkrete Aussage bzgl. der Eignung eines Positionierungssystems treffen zu können. Die Einsetzbarkeit dieses Analyseverfahrens wird an einer Fallstudie verdeutlicht und zeigt die Notwendigkeit einer solchen Analyse bereits vor der Ausbringung von standortbasierter Autorisierung. Es wird gezeigt, dass für typische Positionierungssysteme durch die entwickelten risikobasierten Verfahren eine erhebliche Reduktion von Schaden aus Falschentscheidungen möglich ist und die Einsetzbarkeit der standortbasierten Autorisierung somit verbessert werden kann.The increasing technical capabilities of mobile devices allow a broad range of new applications. For example, employees are allowed to work mobile or industrial production processes can be remotely controlled via the mobile. For reasons of information security and operational safety, as well as for implementing functional requirements, often the availability of according access rights needs to be restricted to users within an authorized zone. Thus, access to sensitive data can be bound to users within particular offices, or the remote control of industrial machines can be restricted to safe regions within the factory building. For that purpose, the position of the user needs to be determined. Unfortunately, positioning errors in the size of authorized zones can arise during operation. Up to now, there are no approaches that handle those positioning errors when access rights are derived in a way, that minimizes negative consequences of possibly false authorization decisions. Furthermore, there are no methods to analyze the quality of such location constraints in the forefront of their deployment with a specific positioning system. Thus, it is left unclear, if its positioning errors are acceptable in the according scenario. In order to solve these problems, this thesis presents approaches to comprehend and handle positioning errors in the field of location-based access control. First of all, an error estimator for pattern-based positioning systems is introduced that employes characteristics of conducted position measurements. A probability density function (pdf) is derived in order to model the user's real position. This pdf can be used to derive the probability that a user is within the authorized zone. An algorithm is presented that employes precomputations to derive this probability. It allows for highly increased performance compared to the direct computation. For the first time, a detailed comparison of existing strategies for location-based access control is presented based on decision theory. The risk-based strategy is introduced, which is a novel method that is optimal from decision theory's point of view. Several approaches are presented that allow the assignment of location constraints to access control policies. When enforced, those constraints respect risk stemming from uncertain position measurements and possible damage of false authorization decisions. Feature models are introduced as a generalization of polygons for the specification of location constraints. For each geographic point, those models describe the probability that a required feature can be observed. Furthermore, a method is presented that allows to reduce the impact of measurement outliers on authorization decisions. At last, methods are presented that allow for a qualitative and quantitative rating of positioning systems for a given scenario. The quantitative rating is based on the novel concept of authorization models. Those models describe the probabiltiy for each geographic point, that a user at this point gets a position estimate that leads to an authorization. The qualitative rating represents a binary criteria to judge the suitability of a positioning system in a given scenario. The applicability of this method is demonstrated by a case study. This case study also brings up the necessity of such an analysis already before location-based access control is deployed. It is shown that for typical positioning systems the damage caused by false authorization decisions can be highly reduced by using the developed risk-based strategy. Finally, this improves the applicability of location-based access control, when positioning errors are non-negligible

Erfassung und Behandlung von Positionsfehlern in standortbasierter Autorisierung

Durch die immer größeren technischen Möglichkeiten mobiler Endgeräte sind die Voraussetzungen erfüllt, um diese zum mobilen Arbeiten oder zur Steuerung von industriellen Fertigungsprozessen einzusetzen. Aus Gründen der Informations- und Betriebssicherheit, sowie zur Umsetzung funktionaler Anforderungen, ist es aber vielfach erforderlich, die Verfügbarkeit von entsprechenden Zugriffsrechten auf Nutzer innerhalb autorisierter Zonen zu begrenzen. So kann z.B. das Auslesen kritischer Daten auf individuelle Büros oder die mobile Steuerung von Maschinen auf passende Orte innerhalb einer Fabrikhalle beschränkt werden. Dazu muss die Position des Nutzers ermittelt werden. Im realen Einsatz können Positionsschätzungen jedoch mit Fehlern in der Größe von autorisierten Zonen auftreten. Derzeit existieren noch keine Lösungen, welche diese Fehler in Autorisierungsentscheidungen berücksichtigen, um einhergehenden Schaden aus Falschentscheidungen zu minimieren. Ferner existieren derzeit keine Verfahren, um die Güteeigenschaften solcher Ortsbeschränkungen vor deren Ausbringung zu analysieren und zu entscheiden, ob ein gegebenes Positionierungssystem aufgrund der Größe seiner Positionsfehler geeignet ist. In der vorliegenden Arbeit werden deshalb Lösungen zur Erfassung und Behandlung solcher Positionsfehler im Umfeld der standortbasierten Autorisierung vorgestellt. Hierzu wird zunächst ein Schätzverfahren für Positionsfehler in musterbasierten Positionierungsverfahren eingeführt, das aus den Charakteristika der durchgeführten Messungen eine Verteilung für den Standort des Nutzers ableitet. Um hieraus effizient die Aufenthaltswahrscheinlichkeit innerhalb einer autorisierten Zone zu bestimmen, wird ein Algorithmus vorgestellt, der basierend auf Vorberechnungen eine erhebliche Verbesserung der Laufzeit gegenüber der direkten Berechnung erlaubt. Erstmals wird eine umfassende Gegenüberstellung von existierenden standortbasierten Autorisierungsstrategien auf Basis der Entscheidungstheorie vorgestellt. Mit der risikobasierten Autorisierungsstrategie wird eine neue, aus entscheidungstheoretischer Sicht optimale Methodik eingeführt. Es werden Ansätze zur Erweiterung klassischer Zugriffskontrollmodelle durch Ortsbeschränkungen vorgestellt, welche bei ihrer Durchsetzung die Möglichkeit von Positionsfehlern und die Konsequenzen von Falschentscheidungen berücksichtigen. Zur Spezifikation autorisierter Zonen werden Eigenschaftsmodelle eingeführt, die, im Gegensatz zu herkömmlichen Polygonen, für jeden Ort die Wahrscheinlichkeit modellieren, dort eine geforderte Eigenschaft zu beobachten. Es werden ferner Methoden vorgestellt, um den Einfluss von Messausreißern auf Autorisierungsentscheidungen zu reduzieren. Ferner werden Analyseverfahren eingeführt, die für ein gegebenes Szenario eine qualitative und quantitative Bewertung der Eignung von Positionierungssystemen erlauben. Die quantitative Bewertung basiert auf dem entwickelten Konzept der Autorisierungsmodelle. Diese geben für jeden Standort die Wahrscheinlichkeit an, dort eine Positionsschätzung zu erhalten, die zur Autorisierung führt. Die qualitative Bewertung bietet erstmals ein binäres Kriterium, um für ein gegebenes Szenario eine konkrete Aussage bzgl. der Eignung eines Positionierungssystems treffen zu können. Die Einsetzbarkeit dieses Analyseverfahrens wird an einer Fallstudie verdeutlicht und zeigt die Notwendigkeit einer solchen Analyse bereits vor der Ausbringung von standortbasierter Autorisierung. Es wird gezeigt, dass für typische Positionierungssysteme durch die entwickelten risikobasierten Verfahren eine erhebliche Reduktion von Schaden aus Falschentscheidungen möglich ist und die Einsetzbarkeit der standortbasierten Autorisierung somit verbessert werden kann.The increasing technical capabilities of mobile devices allow a broad range of new applications. For example, employees are allowed to work mobile or industrial production processes can be remotely controlled via the mobile. For reasons of information security and operational safety, as well as for implementing functional requirements, often the availability of according access rights needs to be restricted to users within an authorized zone. Thus, access to sensitive data can be bound to users within particular offices, or the remote control of industrial machines can be restricted to safe regions within the factory building. For that purpose, the position of the user needs to be determined. Unfortunately, positioning errors in the size of authorized zones can arise during operation. Up to now, there are no approaches that handle those positioning errors when access rights are derived in a way, that minimizes negative consequences of possibly false authorization decisions. Furthermore, there are no methods to analyze the quality of such location constraints in the forefront of their deployment with a specific positioning system. Thus, it is left unclear, if its positioning errors are acceptable in the according scenario. In order to solve these problems, this thesis presents approaches to comprehend and handle positioning errors in the field of location-based access control. First of all, an error estimator for pattern-based positioning systems is introduced that employes characteristics of conducted position measurements. A probability density function (pdf) is derived in order to model the user's real position. This pdf can be used to derive the probability that a user is within the authorized zone. An algorithm is presented that employes precomputations to derive this probability. It allows for highly increased performance compared to the direct computation. For the first time, a detailed comparison of existing strategies for location-based access control is presented based on decision theory. The risk-based strategy is introduced, which is a novel method that is optimal from decision theory's point of view. Several approaches are presented that allow the assignment of location constraints to access control policies. When enforced, those constraints respect risk stemming from uncertain position measurements and possible damage of false authorization decisions. Feature models are introduced as a generalization of polygons for the specification of location constraints. For each geographic point, those models describe the probability that a required feature can be observed. Furthermore, a method is presented that allows to reduce the impact of measurement outliers on authorization decisions. At last, methods are presented that allow for a qualitative and quantitative rating of positioning systems for a given scenario. The quantitative rating is based on the novel concept of authorization models. Those models describe the probabiltiy for each geographic point, that a user at this point gets a position estimate that leads to an authorization. The qualitative rating represents a binary criteria to judge the suitability of a positioning system in a given scenario. The applicability of this method is demonstrated by a case study. This case study also brings up the necessity of such an analysis already before location-based access control is deployed. It is shown that for typical positioning systems the damage caused by false authorization decisions can be highly reduced by using the developed risk-based strategy. Finally, this improves the applicability of location-based access control, when positioning errors are non-negligible

Towards movement-aware access control

The objective of spatially-aware access control models is to regulate the access to protected objects based on position information. In that last years, increasing attention has been paid to spatially-aware access control models for mobile and pervasive applications. Following the experience of design of the GEO-RBAC model, in this paper we want to look at those models with a critical eye and point out open conceptual and architectural challenges. In this paper, we first discuss architectural issues related to the development of a multi-domain access control system based on GEO-RBAC. Then we present the guidelines of a novel and space-centric modeling framework which aims at overcoming the conceptual limitations of the present model and similar solutions