15,403 research outputs found
The Viability and Potential Consequences of IoT-Based Ransomware
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
Technical Dimensions of Programming Systems
Programming requires much more than just writing code in a programming language. It is usually done in the context of a stateful environment, by interacting with a system through a graphical user interface. Yet, this wide space of possibilities lacks a common structure for navigation. Work on programming systems fails to form a coherent body of research, making it hard to improve on past work and advance the state of the art.
In computer science, much has been said and done to allow comparison of programming languages, yet no similar theory exists for programming systems; we believe that programming systems deserve a theory too.
We present a framework of technical dimensions which capture the underlying characteristics of programming systems and provide a means for conceptualizing and comparing them.
We identify technical dimensions by examining past influential programming systems and reviewing their design principles, technical capabilities, and styles of user interaction. Technical dimensions capture characteristics that may be studied, compared and advanced independently. This makes it possible to talk about programming systems in a way that can be shared and constructively debated rather than relying solely on personal impressions.
Our framework is derived using a qualitative analysis of past programming systems. We outline two concrete ways of using our framework. First, we show how it can analyze a recently developed novel programming system. Then, we use it to identify an interesting unexplored point in the design space of programming systems.
Much research effort focuses on building programming systems that are easier to use, accessible to non-experts, moldable and/or powerful, but such efforts are disconnected. They are informal, guided by the personal vision of their authors and thus are only evaluable and comparable on the basis of individual experience using them. By providing foundations for more systematic research, we can help programming systems researchers to stand, at last, on the shoulders of giants
Kurcuma: a kitchen utensil recognition collection for unsupervised domain adaptation
The use of deep learning makes it possible to achieve extraordinary results in all kinds of tasks related to computer vision. However, this performance is strongly related to the availability of training data and its relationship with the distribution in the eventual application scenario. This question is of vital importance in areas such as robotics, where the targeted environment data are barely available in advance. In this context, domain adaptation (DA) techniques are especially important to building models that deal with new data for which the corresponding label is not available. To promote further research in DA techniques applied to robotics, this work presents Kurcuma (Kitchen Utensil Recognition Collection for Unsupervised doMain Adaptation), an assortment of seven datasets for the classification of kitchen utensils—a task of relevance in home-assistance robotics and a suitable showcase for DA. Along with the data, we provide a broad description of the main characteristics of the dataset, as well as a baseline using the well-known domain-adversarial training of neural networks approach. The results show the challenge posed by DA on these types of tasks, pointing to the need for new approaches in future work.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the I+D+i project TED2021-132103A-I00 (DOREMI), funded by MCIN/AEI/10.13039/501100011033. Some of the computing resources were provided by the Generalitat Valenciana and the European Union through the FEDER funding program (IDIFEDER/2020/003). The second author is supported by grant APOSTD/2020/256 from “Programa I+D+i de la Generalitat Valenciana”
Countermeasures for the majority attack in blockchain distributed systems
La tecnologĂa Blockchain es considerada como uno de los paradigmas informáticos más importantes posterior al Internet; en funciĂłn a sus caracterĂsticas Ăşnicas que la hacen ideal para registrar, verificar y administrar informaciĂłn 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 extraĂdo o del cĂłmputo en una red; de modo que un minero puede manipular y modificar arbitrariamente la informaciĂłn registrada en esta tecnologĂa. Este trabajo se enfocĂł en diseñar e implementar estrategias de detecciĂłn y mitigaciĂłn de ataques mayoritarios (51% de ataque) en un sistema distribuido Blockchain, a partir de la caracterizaciĂłn del comportamiento de los mineros. Para lograr esto, se analizĂł y evaluĂł el Hash Rate / Share de los mineros de Bitcoin y Crypto Ethereum, seguido del diseño e implementaciĂłn de un protocolo de consenso para controlar el poder de cĂłmputo de los mineros. Posteriormente, se realizĂł la exploraciĂłn y evaluaciĂłn de modelos de Machine Learning para detectar software malicioso de tipo Cryptojacking.DoctoradoDoctor en IngenierĂa de Sistemas y ComputaciĂł
Kirchhoff-Love shell representation and analysis using triangle configuration B-splines
This paper presents the application of triangle configuration B-splines
(TCB-splines) for representing and analyzing the Kirchhoff-Love shell in the
context of isogeometric analysis (IGA). The Kirchhoff-Love shell formulation
requires global -continuous basis functions. The nonuniform rational
B-spline (NURBS)-based IGA has been extensively used for developing
Kirchhoff-Love shell elements. However, shells with complex geometries
inevitably need multiple patches and trimming techniques, where stitching
patches with high continuity is a challenge. On the other hand, due to their
unstructured nature, TCB-splines can accommodate general polygonal domains,
have local refinement, and are flexible to model complex geometries with
continuity, which naturally fit into the Kirchhoff-Love shell formulation with
complex geometries. Therefore, we propose to use TCB-splines as basis functions
for geometric representation and solution approximation. We apply our method to
both linear and nonlinear benchmark shell problems, where the accuracy and
robustness are validated. The applicability of the proposed approach to shell
analysis is further exemplified by performing geometrically nonlinear
Kirchhoff-Love shell simulations of a pipe junction and a front bumper
represented by a single patch of TCB-splines
Interview with Wolfgang Knauss
An oral history in four sessions (September 2019–January 2020) with Wolfgang Knauss, von Kármán Professor of Aeronautics and Applied Mechanics, Emeritus. Born in Germany in 1933, he speaks about his early life and experiences under the Nazi regime, his teenage years in Siegen and Heidelberg during the Allied occupation, and his move to Pasadena, California, in 1954 under the sponsorship of a local minister and his family. He enrolled in Caltech as an undergraduate in 1957, commencing a more than half-century affiliation with the Institute and GALCIT (today the Graduate Aerospace Laboratories of Caltech). He recalls the roots of his interest in aeronautics, his PhD solid mechanics studies with his advisor, M. Williams, and the GALCIT environment in the late 1950s and 1960s at the dawn of the Space Age, including the impact of Sputnik and classes with NASA astronauts. He discusses his experimental and theoretical work on materials deformation, dynamic fracture, and crack propagation, including his solid-propellant fuels research for NASA and the US Army, wide-ranging programs with the US Navy, and his pioneering micromechanics investigations and work on the time-dependent fracture of polymers in the 1990s.
He offers his perspective on GALCIT’s academic culture, its solid mechanics and fluid mechanics programs, and its evolving administrative directions over the course of five decades, as well as its impact and reputation both within and beyond Caltech. He describes his work with Caltech’s undergraduate admissions committee and his scientific collaborations with numerous graduate students and postdocs and shares his recollections of GALCIT and other Caltech colleagues, including C. Babcock, D. Coles, R.P. Feynman, Y.C. Fung, G. Neugebauer, G. Housner, D. Hudson, H. Liepmann, A. Klein, G. Ravichandran, A. Rosakis, A. Roshko, and E. Sechler.
Six appendices contributed by Dr. Knauss, offering further insight into his life and career, also form part of this oral history and are cross-referenced in the main text
Fiabilité de l’underfill et estimation de la durée de vie d’assemblages microélectroniques
Abstract : In order to protect the interconnections in flip-chip packages, an underfill material layer
is used to fill the volumes and provide mechanical support between the silicon chip and
the substrate. Due to the chip corner geometry and the mismatch of coefficient of thermal
expansion (CTE), the underfill suffers from a stress concentration at the chip corners when
the temperature is lower than the curing temperature. This stress concentration leads
to subsequent mechanical failures in flip-chip packages, such as chip-underfill interfacial
delamination and underfill cracking. Local stresses and strains are the most important
parameters for understanding the mechanism of underfill failures. As a result, the industry
currently relies on the finite element method (FEM) to calculate the stress components, but
the FEM may not be accurate enough compared to the actual stresses in underfill. FEM
simulations require a careful consideration of important geometrical details and material
properties. This thesis proposes a modeling approach that can accurately estimate the underfill delamination
areas and crack trajectories, with the following three objectives. The first
objective was to develop an experimental technique capable of measuring underfill deformations
around the chip corner region. This technique combined confocal microscopy and
the digital image correlation (DIC) method to enable tri-dimensional strain measurements
at different temperatures, and was named the confocal-DIC technique. This techique was
first validated by a theoretical analysis on thermal strains. In a test component similar
to a flip-chip package, the strain distribution obtained by the FEM model was in good
agreement with the results measured by the confocal-DIC technique, with relative errors
less than 20% at chip corners. Then, the second objective was to measure the strain near
a crack in underfills. Artificial cracks with lengths of 160 ÎĽm and 640 ÎĽm were fabricated
from the chip corner along the 45° diagonal direction. The confocal-DIC-measured
maximum hoop strains and first principal strains were located at the crack front area for
both the 160 ÎĽm and 640 ÎĽm cracks. A crack model was developed using the extended
finite element method (XFEM), and the strain distribution in the simulation had the same
trend as the experimental results. The distribution of hoop strains were in good agreement
with the measured values, when the model element size was smaller than 22 ÎĽm to
capture the strong strain gradient near the crack tip. The third objective was to propose
a modeling approach for underfill delamination and cracking with the effects of manufacturing
variables. A deep thermal cycling test was performed on 13 test cells to obtain the
reference chip-underfill delamination areas and crack profiles. An artificial neural network
(ANN) was trained to relate the effects of manufacturing variables and the number of
cycles to first delamination of each cell. The predicted numbers of cycles for all 6 cells in
the test dataset were located in the intervals of experimental observations. The growth
of delamination was carried out on FEM by evaluating the strain energy amplitude at
the interface elements between the chip and underfill. For 5 out of 6 cells in validation,
the delamination growth model was consistent with the experimental observations. The
cracks in bulk underfill were modelled by XFEM without predefined paths. The directions of edge cracks were in good agreement with the experimental observations, with an error
of less than 2.5°. This approach met the goal of the thesis of estimating the underfill
initial delamination, areas of delamination and crack paths in actual industrial flip-chip
assemblies.Afin de protéger les interconnexions dans les assemblages, une couche de matériau d’underfill est utilisée pour remplir le volume et fournir un support mécanique entre la puce de silicium et le substrat. En raison de la géométrie du coin de puce et de l’écart du coefficient de dilatation thermique (CTE), l’underfill souffre d’une concentration de contraintes dans les coins lorsque la température est inférieure à la température de cuisson. Cette concentration de contraintes conduit à des défaillances mécaniques dans les encapsulations de flip-chip, telles que la délamination interfaciale puce-underfill et la fissuration d’underfill. Les contraintes et déformations locales sont les paramètres les plus importants pour comprendre le mécanisme des ruptures de l’underfill. En conséquent, l’industrie utilise actuellement la méthode des éléments finis (EF) pour calculer les composantes de la contrainte, qui ne sont pas assez précises par rapport aux contraintes actuelles dans l’underfill. Ces simulations nécessitent un examen minutieux de détails géométriques importants et des propriétés des matériaux. Cette thèse vise à proposer une approche de modélisation permettant d’estimer avec précision les zones de délamination et les trajectoires des fissures dans l’underfill, avec les trois objectifs suivants. Le premier objectif est de mettre au point une technique expérimentale capable de mesurer la déformation de l’underfill dans la région du coin de puce. Cette technique, combine la microscopie confocale et la méthode de corrélation des images numériques (DIC) pour permettre des mesures tridimensionnelles des déformations à différentes températures, et a été nommée le technique confocale-DIC. Cette technique a d’abord été validée par une analyse théorique en déformation thermique. Dans un échantillon similaire à un flip-chip, la distribution de la déformation obtenues par le modèle EF était en bon accord avec les résultats de la technique confocal-DIC, avec des erreurs relatives inférieures à 20% au coin de puce. Ensuite, le second objectif est de mesurer la déformation autour d’une fissure dans l’underfill. Des fissures artificielles d’une longueuer de 160 μm et 640 μm ont été fabriquées dans l’underfill vers la direction diagonale de 45°. Les déformations circonférentielles maximales et principale maximale étaient situées aux pointes des fissures correspondantes. Un modèle de fissure a été développé en utilisant la méthode des éléments finis étendue (XFEM), et la distribution des contraintes dans la simuation a montré la même tendance que les résultats expérimentaux. La distribution des déformations circonférentielles maximales était en bon accord avec les valeurs mesurées lorsque la taille des éléments était plus petite que 22 μm, assez petit pour capturer le grand gradient de déformation près de la pointe de fissure. Le troisième objectif était d’apporter une approche de modélisation de la délamination et de la fissuration de l’underfill avec les effets des variables de fabrication. Un test de cyclage thermique a d’abord été effectué sur 13 cellules pour obtenir les zones délaminées entre la puce et l’underfill, et les profils de fissures dans l’underfill, comme référence. Un réseau neuronal artificiel (ANN) a été formé pour établir une liaison entre les effets des variables de fabrication et le nombre de cycles à la délamination pour chaque cellule. Les nombres de cycles prédits pour les 6 cellules de l’ensemble de test étaient situés dans les intervalles d’observations expérimentaux. La croissance de la délamination a été réalisée par l’EF en évaluant l’énergie de la déformation au niveau des éléments interfaciaux entre la puce et l’underfill. Pour 5 des 6 cellules de la validation, le modèle de croissance du délaminage était conforme aux observations expérimentales. Les fissures dans l’underfill ont été modélisées par XFEM sans chemins prédéfinis. Les directions des fissures de bord étaient en bon accord avec les observations expérimentales, avec une erreur inférieure à 2,5°. Cette approche a répondu à la problématique qui consiste à estimer l’initiation des délamination, les zones de délamination et les trajectoires de fissures dans l’underfill pour des flip-chips industriels
How to Be a God
When it comes to questions concerning the nature of Reality, Philosophers and Theologians have the answers.
Philosophers have the answers that can’t be proven right. Theologians have the answers that can’t be proven wrong.
Today’s designers of Massively-Multiplayer Online Role-Playing Games create realities for a living. They can’t spend centuries mulling over the issues: they have to face them head-on. Their practical experiences can indicate which theoretical proposals actually work in practice.
That’s today’s designers. Tomorrow’s will have a whole new set of questions to answer.
The designers of virtual worlds are the literal gods of those realities. Suppose Artificial Intelligence comes through and allows us to create non-player characters as smart as us. What are our responsibilities as gods? How should we, as gods, conduct ourselves?
How should we be gods
A productive response to legacy system petrification
Requirements change. The requirements of a legacy information system change, often in unanticipated ways, and at a more rapid pace than the rate at which the information system itself can be evolved to support them. The capabilities of a legacy system progressively fall further and further behind their evolving requirements, in a degrading process termed petrification. As systems petrify, they deliver diminishing business value, hamper business effectiveness, and drain organisational resources. To address legacy systems, the first challenge is to understand how to shed their resistance to tracking requirements change. The second challenge is to ensure that a newly adaptable system never again petrifies into a change resistant legacy system. This thesis addresses both challenges. The approach outlined herein is underpinned by an agile migration process - termed Productive Migration - that homes in upon the specific causes of petrification within each particular legacy system and provides guidance upon how to address them. That guidance comes in part from a personalised catalogue of petrifying patterns, which capture recurring themes underlying petrification. These steer us to the problems actually present in a given legacy system, and lead us to suitable antidote productive patterns via which we can deal with those problems one by one. To prevent newly adaptable systems from again degrading into legacy systems, we appeal to a follow-on process, termed Productive Evolution, which embraces and keeps pace with change rather than resisting and falling behind it. Productive Evolution teaches us to be vigilant against signs of system petrification and helps us to nip them in the bud. The aim is to nurture systems that remain supportive of the business, that are adaptable in step with ongoing requirements change, and that continue to retain their value as significant business assets
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