14,304 research outputs found

    Sistema de bloqueio de computadores

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    Mestrado em Engenharia de Computadores e TelemáticaThe use of multiple computing devices per person is increasing more and more. Nowadays is normal that mobile devices like smartphones, tablets and laptops are present in the everyday life of a single person and in many cases people use these devices to perform important operations related with their professional life. This also presents a problem, as these devices come with the user in everyday life and the fact that often they have a high monetary value means that these devices are susceptible to theft. This thesis introduces a computer locking system that distinguishes itself from existing similar systems because (i) it is designed to work independently of the Operating System(s) installed on the laptop or mobile device, (ii) depends on a firrmware driver that implements the lock operation making it resistant to storage device formats or any other attack that uses software operations. It is also explored the operation of a device that has a firrmware that follows the Unified Extensible Firmware Interface (UEFI) specification as well as the development of drivers for this type of firrmware. It was also developed a security protocol and various cryptographic techniques where explored and implemented.O uso de vários dispositivos computacionais por pessoa está a aumentar cada vez mais. Hoje em dia é normal dispositivos móveis como o smartphone, tablet e computador portátil estarem presentes no quotidiano das pessoas e em muitos casos as pessoas necessitam de realizar tarefas na sua vida profissional nestes dispositivos. Isto apresenta também um problema, como estes dispositivos acompanham o utilizador no dia a dia e pelo facto de muitas vezes terem um valor monetário elevado faz com que estes dispositivos sejam suscetíveis a roubos. Esta tese introduz um sistema de bloqueio de computadores que se distingue dos sistemas similares existentes porque, (i) _e desenhado para funcionar independentemente do(s) sistema(s) operativo(s) instalado(s) no computador portátil ou no dispositivo móvel, (ii) depende de um driver do firrmware que concretiza a operação de bloqueio fazendo com que seja resistente contra formatação do dispositivo de armazenamento ou qualquer outro ataque que tenho por base a utilização de software. É explorado então o funcionamento de um dispositivo que tenha um firmware que respeita a especificação Unfied Extensible Firmware Interface (UEFI) assim como a programação de drivers para este tipo de firmware. Foi também desenvolvido um protocolo de segurança e são exploradas várias técnicas criptográficas passiveis de serem implementadas

    The Viability and Potential Consequences of IoT-Based Ransomware

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    With the increased threat of ransomware and the substantial growth of the Internet of Things (IoT) market, there is significant motivation for attackers to carry out IoT-based ransomware campaigns. In this thesis, the viability of such malware is tested. As part of this work, various techniques that could be used by ransomware developers to attack commercial IoT devices were explored. First, methods that attackers could use to communicate with the victim were examined, such that a ransom note was able to be reliably sent to a victim. Next, the viability of using "bricking" as a method of ransom was evaluated, such that devices could be remotely disabled unless the victim makes a payment to the attacker. Research was then performed to ascertain whether it was possible to remotely gain persistence on IoT devices, which would improve the efficacy of existing ransomware methods, and provide opportunities for more advanced ransomware to be created. Finally, after successfully identifying a number of persistence techniques, the viability of privacy-invasion based ransomware was analysed. For each assessed technique, proofs of concept were developed. A range of devices -- with various intended purposes, such as routers, cameras and phones -- were used to test the viability of these proofs of concept. To test communication hijacking, devices' "channels of communication" -- such as web services and embedded screens -- were identified, then hijacked to display custom ransom notes. During the analysis of bricking-based ransomware, a working proof of concept was created, which was then able to remotely brick five IoT devices. After analysing the storage design of an assortment of IoT devices, six different persistence techniques were identified, which were then successfully tested on four devices, such that malicious filesystem modifications would be retained after the device was rebooted. When researching privacy-invasion based ransomware, several methods were created to extract information from data sources that can be commonly found on IoT devices, such as nearby WiFi signals, images from cameras, or audio from microphones. These were successfully implemented in a test environment such that ransomable data could be extracted, processed, and stored for later use to blackmail the victim. Overall, IoT-based ransomware has not only been shown to be viable but also highly damaging to both IoT devices and their users. While the use of IoT-ransomware is still very uncommon "in the wild", the techniques demonstrated within this work highlight an urgent need to improve the security of IoT devices to avoid the risk of IoT-based ransomware causing havoc in our society. Finally, during the development of these proofs of concept, a number of potential countermeasures were identified, which can be used to limit the effectiveness of the attacking techniques discovered in this PhD research

    TOI-969: a late-K dwarf with a hot mini-Neptune in the desert and an eccentric cold Jupiter

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    Context. The current architecture of a given multi-planetary system is a key fingerprint of its past formation and dynamical evolution history. Long-term follow-up observations are key to complete their picture. Aims. In this paper, we focus on the confirmation and characterization of the components of the TOI-969 planetary system, where TESS detected a Neptune-size planet candidate in a very close-in orbit around a late K-dwarf star. Methods. We use a set of precise radial velocity observations from HARPS, PFS, and CORALIE instruments covering more than two years in combination with the TESS photometric light curve and other ground-based follow-up observations to confirm and characterize the components of this planetary system. Results. We find that TOI-969 b is a transiting close-in (Pb ∼ 1.82 days) mini-Neptune planet (Formula Presented), placing it on the lower boundary of the hot-Neptune desert (Teq,b = 941 \ub1 31 K). The analysis of its internal structure shows that TOI-969 b is a volatile-rich planet, suggesting it underwent an inward migration. The radial velocity model also favors the presence of a second massive body in the system, TOI-969 c, with a long period of (Formula Presented) days, a minimum mass of (Formula Presented), and a highly eccentric orbit of (Formula Presented). Conclusions. The TOI-969 planetary system is one of the few around K-dwarfs known to have this extended configuration going from a very close-in planet to a wide-separation gaseous giant. TOI-969 b has a transmission spectroscopy metric of 93 and orbits a moderately bright (G = 11.3 mag) star, making it an excellent target for atmospheric studies. The architecture of this planetary system can also provide valuable information about migration and formation of planetary systems

    A Benchmark Framework for Data Compression Techniques

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    Lightweight data compression is frequently applied in main memory database systems to improve query performance. The data processed by such systems is highly diverse. Moreover, there is a high number of existing lightweight compression techniques. Therefore, choosing the optimal technique for a given dataset is non-trivial. Existing approaches are based on simple rules, which do not suffice for such a complex decision. In contrast, our vision is a cost-based approach. However, this requires a detailed cost model, which can only be obtained from a systematic benchmarking of many compression algorithms on many different datasets. A naïve benchmark evaluates every algorithm under consideration separately. This yields many redundant steps and is thus inefficient. We propose an efficient and extensible benchmark framework for compression techniques. Given an ensemble of algorithms, it minimizes the overall run time of the evaluation. We experimentally show that our approach outperforms the naïve approach

    Countermeasures for the majority attack in blockchain distributed systems

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    La tecnología Blockchain es considerada como uno de los paradigmas informáticos más importantes posterior al Internet; en función a sus características únicas que la hacen ideal para registrar, verificar y administrar información de diferentes transacciones. A pesar de esto, Blockchain se enfrenta a diferentes problemas de seguridad, siendo el ataque del 51% o ataque mayoritario uno de los más importantes. Este consiste en que uno o más mineros tomen el control de al menos el 51% del Hash extraído o del cómputo en una red; de modo que un minero puede manipular y modificar arbitrariamente la información registrada en esta tecnología. Este trabajo se enfocó en diseñar e implementar estrategias de detección y mitigación de ataques mayoritarios (51% de ataque) en un sistema distribuido Blockchain, a partir de la caracterización del comportamiento de los mineros. Para lograr esto, se analizó y evaluó el Hash Rate / Share de los mineros de Bitcoin y Crypto Ethereum, seguido del diseño e implementación de un protocolo de consenso para controlar el poder de cómputo de los mineros. Posteriormente, se realizó la exploración y evaluación de modelos de Machine Learning para detectar software malicioso de tipo Cryptojacking.DoctoradoDoctor en Ingeniería de Sistemas y Computació

    High-performance and Scalable Software-based NVMe Virtualization Mechanism with I/O Queues Passthrough

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    NVMe(Non-Volatile Memory Express) is an industry standard for solid-state drives (SSDs) that has been widely adopted in data centers. NVMe virtualization is crucial in cloud computing as it allows for virtualized NVMe devices to be used by virtual machines (VMs), thereby improving the utilization of storage resources. However, traditional software-based solutions have flexibility benefits but often come at the cost of performance degradation or high CPU overhead. On the other hand, hardware-assisted solutions offer high performance and low CPU usage, but their adoption is often limited by the need for special hardware support or the requirement for new hardware development. In this paper, we propose LightIOV, a novel software-based NVMe virtualization mechanism that achieves high performance and scalability without consuming valuable CPU resources and without requiring special hardware support. LightIOV can support thousands of VMs on each server. The key idea behind LightIOV is NVMe hardware I/O queues passthrough, which enables VMs to directly access I/O queues of NVMe devices, thus eliminating virtualization overhead and providing near-native performance. Results from our experiments show that LightIOV can provide comparable performance to VFIO, with an IOPS of 97.6%-100.2% of VFIO. Furthermore, in high-density VMs environments, LightIOV achieves 31.4% lower latency than SPDK-Vhost when running 200 VMs, and an improvement of 27.1% in OPS performance in real-world applications

    The Artist as Surveillant: The Use of Surveillance Technology in Contemporary Art

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    Artists have long been called observers, voyeurs, and watchers, and with a particular interest in human behavior and society, they frequently use unknowing passersby as their subjects for works. Curators and scholars explored how artists put citizens under surveillance with photography and videography, which dates back to the early 1900s, years before governments deployed surveillance systems. Since the 1980s, artists have explicitly explored surveillance technology and theory to alert viewers to the rise of surveillance. Today, this genre is called artveillance, a term coined by Andrea Mubi Brighenti in 2010 to categorize art that explicitly deals with surveillance. This genre developed parallel to the rise of mass surveillance which created the current-day surveillance state. Since artveillance dominates the contemporary art scene, I was interested in the history of surveillance technology and themes in art. Although that history is brief, there is a wealth of artworks and studies on the topic. This thesis explores artists who use surveillance technology, specifically close-circuit video, in their practice and how this work has changed over time compared to the rise of government surveillance systems. To properly examine the artwork, each artwork’s technological history and broader cultural context is considered, with careful attention to the artists’ intentions. The thesis starts in the 1970s with Bruce Nauman and Peter Campus’s closed-circuit video installations. The artists did not aim to create a surveillance area but wanted to explore the viewer’s identity with their moving image. In Chapter 2, Julia Scher and Lynn Hershman Leeson’s work from the 1980s and early 1990s is discussed. Created when state surveillance was on the rise, the artists’ work used surveillance technology to critique the systems. The third chapter explores surveillance in a post-9/11 state through Jill Magid and Laura Poitras’s work. The artists exploited and exposed government systems to show how the public’s privacy is invaded. Finally, the paper concludes with an investigation into the public’s relationship with video surveillance, which resembles an apathetic acceptance

    Implementing and Evaluating Security in O-RAN: Interfaces, Intelligence, and Platforms

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    The Open Radio Access Network (RAN) is a networking paradigm that builds on top of cloud-based, multi-vendor, open and intelligent architectures to shape the next generation of cellular networks for 5G and beyond. While this new paradigm comes with many advantages in terms of observatibility and reconfigurability of the network, it inevitably expands the threat surface of cellular systems and can potentially expose its components to several cyber attacks, thus making securing O-RAN networks a necessity. In this paper, we explore the security aspects of O-RAN systems by focusing on the specifications and architectures proposed by the O-RAN Alliance. We address the problem of securing O-RAN systems with an holistic perspective, including considerations on the open interfaces used to interconnect the different O-RAN components, on the overall platform, and on the intelligence used to monitor and control the network. For each focus area we identify threats, discuss relevant solutions to address these issues, and demonstrate experimentally how such solutions can effectively defend O-RAN systems against selected cyber attacks. This article is the first work in approaching the security aspect of O-RAN holistically and with experimental evidence obtained on a state-of-the-art programmable O-RAN platform, thus providing unique guideline for researchers in the field.Comment: 7 pages, 5 figures, 1 table, submitted to IEEE Network Magazin

    Defining Service Level Agreements in Serverless Computing

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    The emergence of serverless computing has brought significant advancements to the delivery of computing resources to cloud users. With the abstraction of infrastructure, ecosystem, and execution environments, users could focus on their code while relying on the cloud provider to manage the abstracted layers. In addition, desirable features such as autoscaling and high availability became a provider’s responsibility and can be adopted by the user\u27s application at no extra overhead. Despite such advancements, significant challenges must be overcome as applications transition from monolithic stand-alone deployments to the ephemeral and stateless microservice model of serverless computing. These challenges pertain to the uniqueness of the conceptual and implementation models of serverless computing. One of the notable challenges is the complexity of defining Service Level Agreements (SLA) for serverless functions. As the serverless model shifts the administration of resources, ecosystem, and execution layers to the provider, users become mere consumers of the provider’s abstracted platform with no insight into its performance. Suboptimal conditions of the abstracted layers are not visible to the end-user who has no means to assess their performance. Thus, SLA in serverless computing must take into consideration the unique abstraction of its model. This work investigates the Service Level Agreement (SLA) modeling of serverless functions\u27 and serverless chains’ executions. We highlight how serverless SLA fundamentally differs from earlier cloud delivery models. We then propose an approach to define SLA for serverless functions by utilizing resource utilization fingerprints for functions\u27 executions and a method to assess if executions adhere to that SLA. We evaluate the approach’s accuracy in detecting SLA violations for a broad range of serverless application categories. Our validation results illustrate a high accuracy in detecting SLA violations resulting from resource contentions and provider’s ecosystem degradations. We conclude by presenting the empirical validation of our proposed approach, which could detect Execution-SLA violations with accuracy up to 99%
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