Patches to modern operating systems, including bug fixes and security updates, and the reboots and downtime they require, cause tremendous problems for system users and administrators. The aim of this research is to develop a model for dynamic update of operating systems, allowing a system to be patched without the need for a reboot or other service interruption. In this work, a model for dynamic update based on operating system modularity is developed and evaluated using a prototype implementation for the K42 operating system. The prototype is able to update kernel code and data structures, even when the interfaces between kernel modules change. When applying an update, at no point is the system's entire execution blocked, and there is no additional overhead after an update has been applied. The base runtime overhead is also very low. An analysis of the K42 revision history shows that approximately 79% of past performance and bug-fix changes to K42 could be converted to dynamic updates, and the proportion would be even higher if the changes were being developed for dynamic update. The model also extends to other systems such as Linux and BSD, that although structured modularly, are not strictly object-oriented like K42. The experience with this approach shows that dynamic update for operating systems is feasible given a sufficiently-modular system structure, allows maintenance patches and updates to be applied without disruption, and need not constrain system performance.

Techn. University, Diss., 2004--Berlin.

The Border Gateway Protocol (BGP), the main component of core Internet connectivity, suffers vulnerability issues related to the impersonation of the ownership of IP prefixes for Autonomous Systems (ASes). In this context, a number of studies have focused on securing the BGP through several techniques, such as monitoring-based, historical-based and statistical-based behavioural models. In spite of the significant research undertaken, the proposed solutions cannot detect the IP prefix hijack accurately or even differentiate it from other types of attacks that could threaten the performance of the BGP. This research proposes three novel detection methods aimed at tracking the behaviour of BGP edge routers and detecting IP prefix hijacks based on statistical analysis of variance, the attack signature approach and a classification-based technique. The first detection method uses statistical analysis of variance to identify hijacking behaviour through the normal operation of routing information being exchanged among routers and their behaviour during the occurrence of IP prefix hijacking. However, this method failed to find any indication of IP prefix hijacking because of the difficulty of having raw BGP data hijacking-free. The research also proposes another detection method that parses BGP advertisements (announcements) and checks whether IP prefixes are announced or advertised by more than one AS. If so, events are selected for further validation using Regional Internet Registry (RIR) databases to determine whether the ASes announcing the prefixes are owned by the same organisation or different organisations. Advertisements for the same IP prefix made by ASes owned by different organisations are subsequently identified as hijacking events. The proposed algorithm of the detection method was validated using the 2008 YouTube Pakistan hijack event; the analysis demonstrates that the algorithm qualitatively increases the accuracy of detecting IP prefix hijacks. The algorithm is very accurate as long as the RIRs (Regional Internet Registries) are updated concurrently with hijacking detection. The detection method and can be integrated and work with BGP routers separately. Another detection method is proposed to detect IP prefix hijacking using a combination of signature-based (parsing-based) and classification-based techniques. The parsing technique is used as a pre-processing phase before the classification-based method. Some features are extracted based on the connectivity behaviour of the suspicious ASes given by the parsing technique. In other words, this detection method tracks the behaviour of the suspicious ASes and follows up with an analysis of their interaction with directly and indirectly connected neighbours based on a set of features extracted from the ASPATH information about the suspicious ASes. Before sending the extracted feature values to the best five classifiers that can work with the specifications of an implemented classification dataset, the detection method computes the similarity between benign and malicious behaviours to determine to what extent the classifiers can distinguish suspicious behaviour from benign behaviour and then detect the hijacking. Evaluation tests of the proposed algorithm demonstrated that the detection method was able to detect the hijacks with 96% accuracy and can be integrated and work with BGP routers separately.

Un remake-actualisation est un film reprenant l’intrigue et les personnages d’un film de même nationalité réalisé antérieurement. Le remake entretient donc une relation hypertextuelle avec son film source. Cependant, la réalité de son hypertextualité s’avère paradoxale à tous les stades de son existence. Sa production met en lumière différentes dynamiques qui ne coïncident pas nécessairement avec sa déclaration et encore moins avec son interprétation. Le remake cherche donc à se construire en tant que création tout en maintenant un lien plus ou moins marqué avec le film original. Qu’il soit télévisuel ou cinématographique, le remake devient le lieu de confrontation des différentes conceptions du média en question. Mais l’objet répond-il à une norme de création universelle ?L’universalité relative de l’objet illustre à la fois une unification de la conception la plus industrielle du cinéma et de la télévision et une nouvelle façon d’appréhender la création audiovisuelle. / An updating remake is a movie which takes the plot and the characters from a filmof the same nationality released earlier. The remade film develops an hypertextualrelationship with its model. However, its hypertextuality is paradoxical at every stages ofits existence.Its production highlights different working-rules which do not necessarily match itsdeclaration or interpretation. The remake film aims at building itself as a creation and atthe same time, at maintaining a link more or less emphasized with the original motionpicture. Televised or cinematographic, the remake becomes the confrontation place of thedifferent media views. But does the object answer to a universal creative rule?The relative universality of the remakes both shows a unification of the mostindustrial conception of cinema and television and a new way to apprehend the audiovisualcreation.

In this thesis, we analyse different ways of detecting application vulnerabilities on installed software. Based on this research, a prototype will be developed that will validate these findings. The prototype will analyse only known vulnerabilities collected from a database and matched with locally collected data.

This thesis initiates the study of the MAX-CUT problem in fully dynamic graphs. Given a graph $G=(V,E)$, we present the first fully dynamic algorithms to maintain a $\frac{1}{2}$-approximate cut in sublinear update time under edge insertions and deletions to $G$. Our results include the following deterministic algorithms: i) an $O(\Delta)$ \textit{worst-case} update time algorithm, where $\Delta$ denotes the maximum degree of $G$ and ii) an $O(m^{1/2})$ amortized update time algorithm where $m$ denotes the maximum number of edges in $G$ during any sequence of updates. \\ \indent We also give the following randomized algorithms when edge updates come from an oblivious adversary: i) a $\tilde{O}(n^{2/3})$ update time algorithm\footnote{Throughout this thesis, $\tilde{O}$ hides a $O(\text{polylog}(n))$ factor.} to maintain a $\frac{1}{2}$-approximate cut, and ii) a $\min\{\tilde{O}(n^{2/3}), \tilde{O}(\frac{n^{{3/2}+2c_0}}{m^{1/2}})\}$ worst case update time algorithm which maintains a $(\frac{1}{2}-o(1))$-approximate cut for any constant $c_0>0$ with high probability. The latter algorithm is obtained by designing a fully dynamic algorithm to maintain a sparse subgraph with sublinear (in $n$) maximum degree which approximates all large cuts in $G$ with high probability. / Graduate

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No description available.

The emergence of the Internet has sparked a tremendous explosion in the special class of systems called mission critical systems. These systems are so vital to their intended tasks that they must operate continuously. Two problems affect them: unplanned, and therefore disastrous, downtime and planned downtime for software maintenance. As the pressure to keep these systems operating continuously increases, scheduling downtime becomes complex. However, dynamically modifying the mission critical systems without disruption can reduce the need for a planned downtime. Every executing process has an executing code tightly coupled with an associated state, which continuously changes as the code executes. A dynamic modification at this juncture involves modifying the executable code and the state present within the binary image of the associated process. An ill-timed modification can create runtime incompatibilities that are hard to rectify and eventually cause a system crash. The purpose of the research in this thesis is to examine the causes for incompatibilities and propose the design of a dynamic modification technique: Software Hot Swapping. To achieve these objectives, the researcher proposes mechanisms which these incompatibilities can prevent, examines the characteristics and the implementation issues of such mechanisms, and demonstrates dynamic modification with a simple prototype Hot Swapping program. / Master of Science

[pt] O desenvolvimento baseado em sistemas de componentes de software consiste em compor sistemas a partir de unidades de sotfware prontas e reutilizáveis. Muitos sistemas de componentes software em produção, precisam ficar disponíveis durante 24 horas por dia nos 7 dias da semana. Atualizações dinâmicas permitem que os sistemas sejam atualizados sem interromperem a execução dos seus serviços, aplicando a atualização em tempo de execução. Muitas técnicas de atualização dinâmica, na literatura, utilizam aplicações feitas especificamente para cobrir os pontos implementados e poucas utilizam um histórico de necessidades de um sistema real. Este trabalho estuda os principais casos de atualizações que ocorrem em um sistema de componentes de uso extenso, o Openbus, que consiste em uma infraestrutura de integração responsável pela comunicação de diversas aplicações de aquisição, processamento e interpretação de dados. Além deste estudo, implementamos uma solução de atualização dinâmica para acomodar as necessidades deste sistema. Depois, utilizando a solução implementada, apresentamos um teste de sobrecarga e algumas aplicações de atualizações do Openbus. / [en] The component-based development of software systems consists on composing systems from ready and reusable sotfware units. Many software componente systems on production, need to be available 24 hours a day 7 days a week. Dynamic updates allow systems to be upgraded without interrupting the execution of its services, applying the update at runtime. Many dynamics software update techniques in the literature use applications specically implemented to cover the presented points and only a few use a historical need of a real system. This work studies the main cases of updates that occur in a system of components with extensive use, the Openbus, which consists of an integration infrastructure responsible for communication of various applications for acquisition, processing and interpretation of data. In addition to this study, we implement a solution of dynamic software update to accommodate the needs of this system. After, using the implemented solution, we present an overhead test and applications of updates on Openbus.