1,720,956 research outputs found
La Sécurité des Centres de Données : du Navigateur au Niveau de l'Infrastructure
No full textData centers are large clusters of interconnected computers used by organizations to remotely deliver digital services. To support this, they are structured into multiple software layers.One key layer is virtualization, which is extensively employed to isolate services while allowing them to share hardware resources.Virtualization is managed by a component known as the hypervisor, which ensures isolation between guest virtual machines (VMs).Above this layer lies the traditional operating system (OS) layer, which manages the allocation and use of system resources by applications.The application layer, in turn, provides services directly to end users.Web browsers are commonly used to access various services across the internet.Data centers are a foundational element of cloud computing, and with the continued expansion of the cloud and the rise of large language models (LLMs), their importance will grow.Consequently, they have become attractive targets for malicious actors, making security a primary concern for legitimate stakeholders.This thesis focuses on securing vulnerable layers of the data center stack.Our first contribution addresses the security of hypervisors against vulnerability exploitation.We observe that current fault-tolerance mechanisms fail to defend against zero-day denial-of-service (DoS) attacks.In response, we propose HERE, a system that implements live VM replication across heterogeneous hypervisors.By combining replication with software diversity, HERE provides protection against zero-day DoS attacks targeting hypervisors.Our second contribution focuses on web browsers, which rely on JavaScript (JS) runtimes to execute web applications. To improve performance, JS runtimes incorporate Just-In-Time (JIT) compilation engines that perform complex optimization passes during code execution.These optimization mechanisms, however, make JIT engines particularly susceptible to vulnerabilities.Disabling the JIT engine is one option, though it introduces performance penalties.Alternatively, waiting for a patch may leave systems exposed.To bridge this gap, we propose Jitbull, a runtime security mechanism that protects the JS engine between vulnerability disclosure and patch deployment.At each optimization pass, Jitbull compares executing code with known malicious code.If a similarity is detected, the corresponding optimization is deactivated; if not possible, the entire JIT engine is suspended.We demonstrate that Jitbull effectively prevents exploitation using variants of demonstrator code for known vulnerabilities, with minimal performance impact.Les centres de données sont de grands ensembles d’ordinateurs interconnectés utilisés par des organisations pour fournir des services numériques à distance. Pour cela, ils sont structurés en plusieurs couches logicielles.Une couche clé est la virtualisation, largement utilisée pour isoler les services tout en leur permettant de partager les ressources matérielles.La virtualisation est gérée par un composant appelé l’hyperviseur, qui assure l’isolation entre les machines virtuelles (VM) invitées.Au-dessus de cette couche se trouve la couche classique du système d'exploitation (OS), qui gère l’allocation et l’utilisation des ressources par les applications.La couche applicative fournit ensuite des services directement aux utilisateurs finaux. Les navigateurs web sont couramment utilisés pour accéder à divers services via Internet.Les centres de données sont un élément fondamental du cloud, et avec l’expansion continue du cloud ainsi que la montée en puissance des grands modèles de langage (LLM), leur importance ne cessera de croître.Par conséquent, ils deviennent des cibles attractives pour les acteurs malveillants, ce qui fait de la sécurité une préoccupation majeure pour les parties légitimes.Cette thèse se concentre sur la sécurisation des couches vulnérables des centres de données.Notre première contribution porte sur la sécurité des hyperviseurs contre l’exploitation de vulnérabilités.Nous observons que les mécanismes actuels de tolérance aux fautes ne protègent pas efficacement contre les attaques par déni de service (DoS) zero-day.En réponse, nous proposons HERE, un système qui implémente la réplication en direct des VM entre hyperviseurs hétérogènes.En combinant réplication et diversité logicielle, HERE protège les hyperviseurs contre les attaques DoS zero-day.Notre seconde contribution concerne les navigateurs web, qui s’appuient sur des environnements d’exécution JavaScript (JS) pour exécuter les applications web.Pour améliorer les performances, ces environnements intègrent des moteurs de compilation Just-In-Time (JIT) qui effectuent des passes d’optimisation complexes pendant l’exécution.Cependant, ces optimisations rendent les moteurs JIT particulièrement vulnérables.Désactiver complètement le moteur JIT est une option, mais cela entraîne des pénalités de performance importantes.Une autre option consiste à attendre un correctif, ce qui a l'inconvénient de laisser le système vulnérable pendant cette période.Pour répondre à cette problématique, nous proposons Jitbull, un mécanisme de sécurité en temps réel qui protège le moteur JS entre la divulgation de la vulnérabilité et le déploiement du correctif.À chaque passe d’optimisation, Jitbull compare le code en cours d’exécution avec des codes malveillants connus.Si une similarité est détectée, l’optimisation correspondante est désactivée ; si cela n’est pas possible, le moteur JIT entier est suspendu.Nous démontrons que Jitbull empêche efficacement l’exploitation par des variantes de codes démonstrateurs de vulnérabilités connues, avec un impact minimal sur les performances
La Sécurité des Centres de Données : du Navigateur au Niveau de l'Infrastructure
No full textData centers are large clusters of interconnected computers used by organizations to remotely deliver digital services. To support this, they are structured into multiple software layers.One key layer is virtualization, which is extensively employed to isolate services while allowing them to share hardware resources.Virtualization is managed by a component known as the hypervisor, which ensures isolation between guest virtual machines (VMs).Above this layer lies the traditional operating system (OS) layer, which manages the allocation and use of system resources by applications.The application layer, in turn, provides services directly to end users.Web browsers are commonly used to access various services across the internet.Data centers are a foundational element of cloud computing, and with the continued expansion of the cloud and the rise of large language models (LLMs), their importance will grow.Consequently, they have become attractive targets for malicious actors, making security a primary concern for legitimate stakeholders.This thesis focuses on securing vulnerable layers of the data center stack.Our first contribution addresses the security of hypervisors against vulnerability exploitation.We observe that current fault-tolerance mechanisms fail to defend against zero-day denial-of-service (DoS) attacks.In response, we propose HERE, a system that implements live VM replication across heterogeneous hypervisors.By combining replication with software diversity, HERE provides protection against zero-day DoS attacks targeting hypervisors.Our second contribution focuses on web browsers, which rely on JavaScript (JS) runtimes to execute web applications. To improve performance, JS runtimes incorporate Just-In-Time (JIT) compilation engines that perform complex optimization passes during code execution.These optimization mechanisms, however, make JIT engines particularly susceptible to vulnerabilities.Disabling the JIT engine is one option, though it introduces performance penalties.Alternatively, waiting for a patch may leave systems exposed.To bridge this gap, we propose Jitbull, a runtime security mechanism that protects the JS engine between vulnerability disclosure and patch deployment.At each optimization pass, Jitbull compares executing code with known malicious code.If a similarity is detected, the corresponding optimization is deactivated; if not possible, the entire JIT engine is suspended.We demonstrate that Jitbull effectively prevents exploitation using variants of demonstrator code for known vulnerabilities, with minimal performance impact.Les centres de données sont de grands ensembles d’ordinateurs interconnectés utilisés par des organisations pour fournir des services numériques à distance. Pour cela, ils sont structurés en plusieurs couches logicielles.Une couche clé est la virtualisation, largement utilisée pour isoler les services tout en leur permettant de partager les ressources matérielles.La virtualisation est gérée par un composant appelé l’hyperviseur, qui assure l’isolation entre les machines virtuelles (VM) invitées.Au-dessus de cette couche se trouve la couche classique du système d'exploitation (OS), qui gère l’allocation et l’utilisation des ressources par les applications.La couche applicative fournit ensuite des services directement aux utilisateurs finaux. Les navigateurs web sont couramment utilisés pour accéder à divers services via Internet.Les centres de données sont un élément fondamental du cloud, et avec l’expansion continue du cloud ainsi que la montée en puissance des grands modèles de langage (LLM), leur importance ne cessera de croître.Par conséquent, ils deviennent des cibles attractives pour les acteurs malveillants, ce qui fait de la sécurité une préoccupation majeure pour les parties légitimes.Cette thèse se concentre sur la sécurisation des couches vulnérables des centres de données.Notre première contribution porte sur la sécurité des hyperviseurs contre l’exploitation de vulnérabilités.Nous observons que les mécanismes actuels de tolérance aux fautes ne protègent pas efficacement contre les attaques par déni de service (DoS) zero-day.En réponse, nous proposons HERE, un système qui implémente la réplication en direct des VM entre hyperviseurs hétérogènes.En combinant réplication et diversité logicielle, HERE protège les hyperviseurs contre les attaques DoS zero-day.Notre seconde contribution concerne les navigateurs web, qui s’appuient sur des environnements d’exécution JavaScript (JS) pour exécuter les applications web.Pour améliorer les performances, ces environnements intègrent des moteurs de compilation Just-In-Time (JIT) qui effectuent des passes d’optimisation complexes pendant l’exécution.Cependant, ces optimisations rendent les moteurs JIT particulièrement vulnérables.Désactiver complètement le moteur JIT est une option, mais cela entraîne des pénalités de performance importantes.Une autre option consiste à attendre un correctif, ce qui a l'inconvénient de laisser le système vulnérable pendant cette période.Pour répondre à cette problématique, nous proposons Jitbull, un mécanisme de sécurité en temps réel qui protège le moteur JS entre la divulgation de la vulnérabilité et le déploiement du correctif.À chaque passe d’optimisation, Jitbull compare le code en cours d’exécution avec des codes malveillants connus.Si une similarité est détectée, l’optimisation correspondante est désactivée ; si cela n’est pas possible, le moteur JIT entier est suspendu.Nous démontrons que Jitbull empêche efficacement l’exploitation par des variantes de codes démonstrateurs de vulnérabilités connues, avec un impact minimal sur les performances
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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