Today's cybercriminals must carefully manage their network resources to evade detection and maintain profitable businesses. For example, a rogue online enterprise has to have multiple technical and business components in place, to provide the necessary infrastructure to keep the business available. Often, cybercriminals in their effort to protect and maintain their valuable network resources (infrastructures), they manipulate two fundamental Internet protocols; the Domain Name System (DNS) and the Border Gateway Protocol (BGP). A popular countermeasure against cybercriminal infrastructures are Autonomous Systems (AS) reputation systems. Past research efforts have developed several AS reputation systems that monitor the traffic for illicit activities. Unfortunately, these systems have severe limitations; (1) they cannot distinguish between malicious and legitimate but abused ASes, and thus it is not clear how to use them in practice, (2) require direct observation of malicious activity, from many different vantage points and for an extended period of time, thus delaying detection. This dissertation presents empirical studies and a system that help to counteract cybecriminal infrastructures. First, we perform empirical studies that help to advance our understanding, about how these infrastructures operate. We study two representative types of infrastructures: (1) fast-flux service networks which are infrastructures based on DNS manipulation, (b) malicious ASes (hubs of cybercriminal activities) which are infrastructures that are primarily based on BGP manipulation. Second, we build on our observations from these studies, and we design and implement, ASwatch; an AS reputation system that, unlike existing approaches, monitors exclusively the routing level behavior of ASes, to expose malicious ASes sooner. We build ASwatch based on the intuition that, in an attempt to evade possible detection and remediation efforts, malicious ASes exhibit agile routing behavior (e.g. short-lived routes, aggressive re-wiring). We evaluate ASwatch on known malicious ASes, and we compare its performance to a state of the art AS reputation system.

Using computer systems for probabilistic genotyping on DNA evidence in forensic casework is beneficial as it allows a complete analysis of the data available for a wide range of profiles, a range that is limited when analyzed manually. One such software, Bulletproof, uses the exact method as the statistical foundation of its web-based interface to estimate the likelihood ratio of two hypotheses that explain the given evidence. In this investigation, the capability of Bulletproof was examined by analyzing the effects of evidence and reference sample template amount, injection time, and stutter filter utilization on likelihood ratio. In terms of likelihood ratio, deconvolution by the software is more efficient in cases in which evidence samples of high contrast ratios (such as 1:9 vs. 1:1) and low contributor count have high template, and when sample injection times are low. Reference sample template amount and injection time are less impactful than that of evidentiary samples. As with unknown samples, reference samples should be analyzed beforehand and artifacts removed for better deconvolution.

[pt] Ameaças contra a vida, principalmente por disparos de armas de fogo, impulsionam a pesquisa de novos materiais para fabricação de soluções para proteção balística individual. Os compósitos poliméricos reforçados por fibras de polietileno de ultra alto peso molecular revolucionaram esse campo nos últimos 15 anos e têm sido extensivamente estudados, principalmente por suas excepcionais propriedades mecânicas e baixa densidade, visando desenvolver materiais com alta capacidade específica de absorção de energia. Em desacordo, a produção desses compósitos é dominada por poucas empresas no mundo, e sua disponibilidade relativamente limitada, além do fato das placas balísticas serem materiais controlados e de domínio de fabricação restrito, o que dificultou a obtenção de informações. Neste sentido, a presente pesquisa buscou projetar, fabricar e caracterizar seis modelos de placas balísticas para proteção contra disparo de munição de fuzil, utilizando diferentes tipos de compósitos (préimpregnados) com a adição de camada da liga de titânio. A caracterização contou com ensaios de FTIR do CBPF, TGA e DSC da PUC-Rio, ensaio de tração (EMT) das fibras, de dureza, MEV e metalografia no CTEx. A análise do desempenho das placas foi realizada no CAEx e contou com câmera de ultra alta velocidade, equipamentos para ensaios balísticos e equipamento de varredura 3D a laser. Os resultados dos ensaios foram mensurados pela velocidade dos disparos e pela profundidade da deformação da face posterior de 16 placas. Foi possível concluir que a fabricação de protótipos mantendo os valores de espessura ou densidade de área da solução semelhante a de placas controle somente em pré-impregnado foi eficiente. O emprego da chapa da liga de Ti-6Al-4V com espessura de apenas 1mm se deu em substituição de até 30 por cento do material pré-impregnado. Na situação limite, foi possível obter placas que resistiram aos impactos de munição de fuzil com cerca de 95 por cento da velocidade especificada na norma, dentro da tolerância de deformação posterior. / [en] Life threats, mainly from firearms, incentive research into new materials for manufacturing personal ballistic protection. Polymer composites reinforced with ultra high molecular weight polyethylene fiber have revolutionized this field over the last 15 years and have been extensively studied, especially for their exceptional mechanical properties and low density, to develop materials with high specific energy absorption capacity. In disagreement, the production of these composites is dominated by few companies in the world, and their availability is relatively limited, besides the fact that ballistic plates are controlled materials and restricted manufacturing domain, which made it difficult to obtain information. In this sense, the present research aims to design, manufacture and characterize six models of ballistic plates for protection against firing of rifle ammunition, using different types of composites (prepregs) with the addition of a titanium alloy layer. The characterization included FTIR at CBPF, TGA and DSC tests at PUC-Rio, fiber tensile strength, SEM, and metallography at CTEx. The plate performance analysis was performed at CAEx and included an ultra high speed camera, ballistic testing equipment and 3D laser scanning equipment. Test results were measured by firing speed and depth of the back face deformation of 16 plates. It was possible to conclude that the prototyping keeping the thickness or areal density values of the solution similar to control plates only in prepreg was efficient. The use of Ti-6Al-4V alloy plate with thickness of only 1mm by replacing up to 30 percent of prepreg material. In the border situation, it was possible to obtain plates that withstood the impact of rifle ammunition at about 95 percent of the speed specified in the standard, within the back face deformation tolerance.

Les impacts non transfixiants sur les gilets pare-balles sont responsables de lésions non pénétrantes potentiellement létales, regroupées sous le terme d’effets arrière (Behind Armor Blunt Trauma : BABT). De telles lésions fermées se retrouvent également lors d’impacts thoraciques de projectiles d’Armes à Létalité Réduite cinétiques (ALRc). Afin d’améliorer le pouvoir protecteur des protections balistiques et de mieux maitriser le pouvoir vulnérant des ALRc, il est nécessaire de définir un critère lésionnel permettant de prédire l’importance des lésions en cas de traumatisme thoracique fermé de type balistique. Ce critère se doit d’être bien corrélé à la gravité du traumatisme, et de pouvoir être facilement transposable à l’ensemble des systèmes d’évaluation des protections balistiques et des ALRc. La gravité du traumatisme a été définie ici par le volume de la contusion pulmonaire. L’utilisation de cette valeur nécessitait le recours au modèle animal. Or, nous avons démontré que le thorax du modèle porcin n’offrait pas le même comportement biomécanique lors de l’impact que le thorax de l’adulte jeune. Nous avons donc développé un critère, l’impulsion de pression intrathoracique maximale (PImax), basé sur la mesure de la pression intrathoracique lors de l’impact, et donc indépendant du comportement biomécanique de la paroi thoracique vis-à-vis de ses effets sur le poumon. Ce critère très bien corrélé avec le volume de la contusion pulmonaire, quelque soit le type d’impact thoracique balistique (ALRc ou BABT), a l’avantage de pouvoir être transposable aux autres moyens d’évaluations balistiques tels que les modèles numériques ou mécaniques de thorax, afin de s’affranchir de l’expérimentation animale / When non-penetrating, impacts on bulletproof jackets can lead to potentially lethal blunt injuries known as behind armor blunt trauma (BABT). Impacts of less lethal kinetic weapons (LLKW) can also lead to such injuries. To both improve the protection capabilities of the BPJ and better comprehend the ounding potential of the LLKW, we need to design a wounding criterion to predict the injury severity of ballistic blunt thoracic trauma. In one hand, this criterion has to be well correlated with the severity of the injuries, and in the other hand, it has to be easily used with all the LLKW and BPJ assessment systems in use. First, we defined the pulmonary contusion volume as the severity of the injuries. Studying the pulmonary contusion involves the use of animal experiments. But we demonstrated that the biomechanics of the chest wall are different in animals and young adults. Then, we developed the maximum pressure impulse criterion (PImax). As it is based on the intrathoracic pressure measure during the blunt impact, it is independent from the chest wall behavior. This criterion can be used with the other assessment tools as the numerical simulation mechanical chest surrogates. This can help to reduce the use of animal experiments, which is more and more expensive, heavy and questionable on the ethical aspect