Discovering New Vulnerabilities in Computer Systems

Vulnerability research plays a key role in preventing and defending against malicious computer system exploitations. Driven by a multi-billion dollar underground economy, cyber criminals today tirelessly launch malicious exploitations, threatening every aspect of daily computing. to effectively protect computer systems from devastation, it is imperative to discover and mitigate vulnerabilities before they fall into the offensive parties\u27 hands. This dissertation is dedicated to the research and discovery of new design and deployment vulnerabilities in three very different types of computer systems.;The first vulnerability is found in the automatic malicious binary (malware) detection system. Binary analysis, a central piece of technology for malware detection, are divided into two classes, static analysis and dynamic analysis. State-of-the-art detection systems employ both classes of analyses to complement each other\u27s strengths and weaknesses for improved detection results. However, we found that the commonly seen design patterns may suffer from evasion attacks. We demonstrate attacks on the vulnerabilities by designing and implementing a novel binary obfuscation technique.;The second vulnerability is located in the design of server system power management. Technological advancements have improved server system power efficiency and facilitated energy proportional computing. However, the change of power profile makes the power consumption subjected to unaudited influences of remote parties, leaving the server systems vulnerable to energy-targeted malicious exploit. We demonstrate an energy abusing attack on a standalone open Web server, measure the extent of the damage, and present a preliminary defense strategy.;The third vulnerability is discovered in the application of server virtualization technologies. Server virtualization greatly benefits today\u27s data centers and brings pervasive cloud computing a step closer to the general public. However, the practice of physical co-hosting virtual machines with different security privileges risks introducing covert channels that seriously threaten the information security in the cloud. We study the construction of high-bandwidth covert channels via the memory sub-system, and show a practical exploit of cross-virtual-machine covert channels on virtualized x86 platforms

Secured Data Transmission Over Insecure Networks-on-Chip by Modulating Inter-Packet Delays

As the network-on-chip (NoC) integrated into an SoC design can come from an untrusted third party, there is a growing risk that data integrity and security get compromised when supposedly sensitive data flows through such an untrusted NoC. We thus introduce a new method that can ensure secure and secret data transmission over such an untrusted NoC. Essentially, the proposed scheme relies on encoding binary data as delays between packets travelling across the source and destination pair. The maximum data transmission rate of this inter-packet-delay (IPD)-based communication channel can be determined from the analytical model developed in this article. To further improve the undetectability and robustness of the proposed data transmission scheme, a new block coding method and communication protocol are also proposed. Experimental results show that the proposed IPD-based method can achieve a packet error rate (PER) of as low as 0.3% and an effective throughput of $\boldsymbol {2.3\times 10^{5}}$ b/s, outperforming the methods of thermal covert channel, cache covert channel, and circuit-based encryption and, thus, is suitable for secure data transmission in unsecure systems

A survey of timing channels and countermeasures

A timing channel is a communication channel that can transfer information to a receiver/decoder by modulating the timing behavior of an entity. Examples of this entity include the interpacket delays of a packet stream, the reordering packets in a packet stream, or the resource access time of a cryptographic module. Advances in the information and coding theory and the availability of high-performance computing systems interconnected by high-speed networks have spurred interest in and development of various types of timing channels. With the emergence of complex timing channels, novel detection and prevention techniques are also being developed to counter them. In this article, we provide a detailed survey of timing channels broadly categorized into network timing channel, in which communicating entities are connected by a network, and in-system timing channel, in which the communicating entities are within a computing system. This survey builds on the last comprehensive survey by Zander et al. [2007] and considers all three canonical applications of timing channels, namely, covert communication, timing side channel, and network flow watermarking. We survey the theoretical foundations, the implementation, and the various detection and prevention techniques that have been reported in literature. Based on the analysis of the current literature, we discuss potential future research directions both in the design and application of timing channels and their detection and prevention techniques

Data Hiding and Its Applications

Data hiding techniques have been widely used to provide copyright protection, data integrity, covert communication, non-repudiation, and authentication, among other applications. In the context of the increased dissemination and distribution of multimedia content over the internet, data hiding methods, such as digital watermarking and steganography, are becoming increasingly relevant in providing multimedia security. The goal of this book is to focus on the improvement of data hiding algorithms and their different applications (both traditional and emerging), bringing together researchers and practitioners from different research fields, including data hiding, signal processing, cryptography, and information theory, among others

An Empirical Analysis of Security and Privacy in Health and Medical Systems

Healthcare reform, regulation, and adoption of technology such as wearables are substantially changing both the quality of care and how we receive it. For example, health and fitness devices contain sensors that collect data, wireless interfaces to transmit data, and cloud infrastructures to aggregate, analyze, and share data. FDA-defined class III devices such as pacemakers will soon share these capabilities. While technological growth in health care is clearly beneficial, it also brings new security and privacy challenges for systems, users, and regulators. We group these concepts under health and medical systems to connect and emphasize their importance to healthcare. Challenges include how to keep user health data private, how to limit and protect access to data, and how to securely store and transmit data while maintaining interoperability with other systems. The most critical challenge unique to healthcare is how to balance security and privacy with safety and utility concerns. Specifically, a life-critical medical device must fail-open (i.e., work regardless) in the event of an active threat or attack. This dissertation examines some of these challenges and introduces new systems that not only improve security and privacy but also enhance workflow and usability. Usability is important in this context because a secure system that inhibits workflow is often improperly used or circumvented. We present this concern and our solution in its respective chapter. Each chapter of this dissertation presents a unique challenge, or unanswered question, and solution based on empirical analysis. We present a survey of related work in embedded health and medical systems. The academic and regulatory communities greatly scrutinize the security and privacy of these devices because of their primary function of providing critical care. What we find is that securing embedded health and medical systems is hard, done incorrectly, and is analogous to non-embedded health and medical systems such as hospital servers, terminals, and personally owned mobile devices. A policy called bring your own device (BYOD) allows the use and integration of mobile devices in the workplace. We perform an analysis of Apple iMessage which both implicates BYOD in healthcare and secure messaging protocols used by health and medical systems. We analyze direct memory access engines, a special-purpose piece of hardware to transfer data into and out of main memory, and show that we can chain together memory transfers to perform arbitrary computation. This result potentially affects all computing systems used for healthcare. We also examine HTML5 web workers as they provide stealthy computation and covert communication. This finding is relevant to web applications such as personal and electronic health record portals. We design and implement two novel and secure health and medical systems. One is a wearable device that addresses the problem of authenticating a user (e.g., physician) to a terminal in a usable way. The other is a light-weight and low-cost wireless device we call Beacon+. This device extends the design of Apple's iBeacon specification with unspoofable, temporal, and authenticated advertisements; of which, enables secure location sensing applications that could improve numerous healthcare processes

TORKAMELEON. IMPROVING TOR’S CENSORSHIP RESISTANCE WITH K-ANONYMIZATION MEDIA MORPHING COVERT INPUT CHANNELS

Anonymity networks such as Tor and other related tools are powerful means of increas- ing the anonymity and privacy of Internet users’ communications. Tor is currently the most widely used solution by whistleblowers to disclose confidential information and denounce censorship measures, including violations of civil rights, freedom of expres- sion, or guarantees of free access to information. However, recent research studies have shown that Tor is vulnerable to so-called powerful correlation attacks carried out by global adversaries or collaborative Internet censorship parties. In the Tor ”arms race” scenario, we can see that as new censorship, surveillance, and deep correlation tools have been researched, new, improved solutions for preserving anonymity have also emerged. In recent research proposals, unobservable encapsulation of IP packets in covert media channels is one of the most promising defenses against such threat models. They leverage WebRTC-based covert channels as a robust and practical approach against powerful traf- fic correlation analysis. At the same time, these solutions are difficult to combat through the traffic-blocking measures commonly used by censorship authorities. In this dissertation, we propose TorKameleon, a censorship evasion solution de- signed to protect Tor users with increased censorship resistance against powerful traffic correlation attacks executed by global adversaries. The system is based on flexible K- anonymization input circuits that can support TLS tunneling and WebRTC-based covert channels before forwarding users’ original input traffic to the Tor network. Our goal is to protect users from machine and deep learning correlation attacks between incom- ing user traffic and observed traffic at different Tor network relays, such as middle and egress relays. TorKameleon is the first system to implement a Tor pluggable transport based on parameterizable TLS tunneling and WebRTC-based covert channels. We have implemented the TorKameleon prototype and performed extensive validations to ob- serve the correctness and experimental performance of the proposed solution in the Tor environment. With these evaluations, we analyze the necessary tradeoffs between the performance of the standard Tor network and the achieved effectiveness and performance of TorKameleon, capable of preserving the required unobservability properties.Redes de anonimização como o Tor e soluções ou ferramentas semelhantes são meios poderosos de aumentar a anonimidade e a privacidade das comunicações de utilizadores da Internet . O Tor é atualmente a rede de anonimato mais utilizada por delatores para divulgar informações confidenciais e denunciar medidas de censura tais como violações de direitos civis e da liberdade de expressão, ou falhas nas garantias de livre acesso à informação. No entanto, estudos recentes mostram que o Tor é vulnerável a adversários globais ou a entidades que colaboram entre si para garantir a censura online. Neste cenário competitivo e de jogo do “gato e do rato”, é possível verificar que à medida que novas soluções de censura e vigilância são investigadas, novos sistemas melhorados para a preservação de anonimato são também apresentados e refinados. O encapsulamento de pacotes IP em túneis encapsulados em protocolos de media são uma das mais promissoras soluções contra os novos modelos de ataque à anonimidade. Estas soluções alavancam canais encobertos em protocolos de media baseados em WebRTC para resistir a poderosos ataques de correlação de tráfego e a medidas de bloqueios normalmente usadas pelos censores. Nesta dissertação propomos o TorKameleon, uma solução desenhada para protoger os utilizadores da rede Tor contra os mais recentes ataques de correlação feitos por um modelo de adversário global. O sistema é baseado em estratégias de anonimização e reencaminhamento do tráfego do utilizador através de K nós, utilizando também encap- sulamento do tráfego em canais encobertos em túneis TLS ou WebRTC. O nosso objetivo é proteger os utilizadores da rede Tor de ataques de correlação implementados através de modelos de aprendizagem automática feitos entre o tráfego do utilizador que entra na rede Tor e esse mesmo tráfego noutro segmento da rede, como por exemplo nos nós de saída da rede. O TorKameleon é o primeiro sistema a implementar um Tor pluggable transport parametrizável, baseado em túneis TLS ou em canais encobertos em protocolos media. Implementamos um protótipo do sistema e realizamos uma extensa avalição expe- rimental, inserindo a solução no ambiente da rede Tor. Com base nestas avaliações, anali- zamos o tradeoff necessário entre a performance da rede Tor e a eficácia e a performance obtida do TorKameleon, que garante as propriedades de preservação de anonimato

Técnicas de compresión de imágenes hiperespectrales sobre hardware reconfigurable

Tesis de la Universidad Complutense de Madrid, Facultad de Informática, leída el 18-12-2020Sensors are nowadays in all aspects of human life. When possible, sensors are used remotely. This is less intrusive, avoids interferces in the measuring process, and more convenient for the scientist. One of the most recurrent concerns in the last decades has been sustainability of the planet, and how the changes it is facing can be monitored. Remote sensing of the earth has seen an explosion in activity, with satellites now being launched on a weekly basis to perform remote analysis of the earth, and planes surveying vast areas for closer analysis...Los sensores aparecen hoy en día en todos los aspectos de nuestra vida. Cuando es posible, de manera remota. Esto es menos intrusivo, evita interferencias en el proceso de medida, y además facilita el trabajo científico. Una de las preocupaciones recurrentes en las últimas décadas ha sido la sotenibilidad del planeta, y cómo menitoirzar los cambios a los que se enfrenta. Los estudios remotos de la tierra han visto un gran crecimiento, con satélites lanzados semanalmente para analizar la superficie, y aviones sobrevolando grades áreas para análisis más precisos...Fac. de InformáticaTRUEunpu