Advances in Information Security and Privacy

With the recent pandemic emergency, many people are spending their days in smart working and have increased their use of digital resources for both work and entertainment. The result is that the amount of digital information handled online is dramatically increased, and we can observe a significant increase in the number of attacks, breaches, and hacks. This Special Issue aims to establish the state of the art in protecting information by mitigating information risks. This objective is reached by presenting both surveys on specific topics and original approaches and solutions to specific problems. In total, 16 papers have been published in this Special Issue

Framework for privacy-aware content distribution in peer-to- peer networks with copyright protection

The use of peer-to-peer (P2P) networks for multimedia distribution has spread out globally in recent years. This mass popularity is primarily driven by the efficient distribution of content, also giving rise to piracy and copyright infringement as well as privacy concerns. An end user (buyer) of a P2P content distribution system does not want to reveal his/her identity during a transaction with a content owner (merchant), whereas the merchant does not want the buyer to further redistribute the content illegally. Therefore, there is a strong need for content distribution mechanisms over P2P networks that do not pose security and privacy threats to copyright holders and end users, respectively. However, the current systems being developed to provide copyright and privacy protection to merchants and end users employ cryptographic mechanisms, which incur high computational and communication costs, making these systems impractical for the distribution of big files, such as music albums or movies.El uso de soluciones de igual a igual (peer-to-peer, P2P) para la distribución multimedia se ha extendido mundialmente en los últimos años. La amplia popularidad de este paradigma se debe, principalmente, a la distribución eficiente de los contenidos, pero también da lugar a la piratería, a la violación del copyright y a problemas de privacidad. Un usuario final (comprador) de un sistema de distribución de contenidos P2P no quiere revelar su identidad durante una transacción con un propietario de contenidos (comerciante), mientras que el comerciante no quiere que el comprador pueda redistribuir ilegalmente el contenido más adelante. Por lo tanto, existe una fuerte necesidad de mecanismos de distribución de contenidos por medio de redes P2P que no supongan un riesgo de seguridad y privacidad a los titulares de derechos y los usuarios finales, respectivamente. Sin embargo, los sistemas actuales que se desarrollan con el propósito de proteger el copyright y la privacidad de los comerciantes y los usuarios finales emplean mecanismos de cifrado que implican unas cargas computacionales y de comunicaciones muy elevadas que convierten a estos sistemas en poco prácticos para distribuir archivos de gran tamaño, tales como álbumes de música o películas.L'ús de solucions d'igual a igual (peer-to-peer, P2P) per a la distribució multimèdia s'ha estès mundialment els darrers anys. L'àmplia popularitat d'aquest paradigma es deu, principalment, a la distribució eficient dels continguts, però també dóna lloc a la pirateria, a la violació del copyright i a problemes de privadesa. Un usuari final (comprador) d'un sistema de distribució de continguts P2P no vol revelar la seva identitat durant una transacció amb un propietari de continguts (comerciant), mentre que el comerciant no vol que el comprador pugui redistribuir il·legalment el contingut més endavant. Per tant, hi ha una gran necessitat de mecanismes de distribució de continguts per mitjà de xarxes P2P que no comportin un risc de seguretat i privadesa als titulars de drets i els usuaris finals, respectivament. Tanmateix, els sistemes actuals que es desenvolupen amb el propòsit de protegir el copyright i la privadesa dels comerciants i els usuaris finals fan servir mecanismes d'encriptació que impliquen unes càrregues computacionals i de comunicacions molt elevades que fan aquests sistemes poc pràctics per a distribuir arxius de grans dimensions, com ara àlbums de música o pel·lícules

Cybersecurity applications of Blockchain technologies

With the increase in connectivity, the popularization of cloud services, and the rise of the Internet of Things (IoT), decentralized approaches for trust management are gaining momentum. Since blockchain technologies provide a distributed ledger, they are receiving massive attention from the research community in different application fields. However, this technology does not provide cybersecurity by itself. Thus, this thesis first aims to provide a comprehensive review of techniques and elements that have been proposed to achieve cybersecurity in blockchain-based systems. The analysis is intended to target area researchers, cybersecurity specialists and blockchain developers. We present a series of lessons learned as well. One of them is the rise of Ethereum as one of the most used technologies. Furthermore, some intrinsic characteristics of the blockchain, like permanent availability and immutability made it interesting for other ends, namely as covert channels and malicious purposes. On the one hand, the use of blockchains by malwares has not been characterized yet. Therefore, this thesis also analyzes the current state of the art in this area. One of the lessons learned is that covert communications have received little attention. On the other hand, although previous works have analyzed the feasibility of covert channels in a particular blockchain technology called Bitcoin, no previous work has explored the use of Ethereum to establish a covert channel considering all transaction fields and smart contracts. To foster further defence-oriented research, two novel mechanisms are presented on this thesis. First, Zephyrus takes advantage of all Ethereum fields and smartcontract bytecode. Second, Smart-Zephyrus is built to complement Zephyrus by leveraging smart contracts written in Solidity. We also assess the mechanisms feasibility and cost. Our experiments show that Zephyrus, in the best case, can embed 40 Kbits in 0.57 s. for US$1.64, and retrieve them in 2.8 s. Smart-Zephyrus, however, is able to hide a 4 Kb secret in 41 s. While being expensive (around US$ 1.82 per bit), the provided stealthiness might be worth the price for attackers. Furthermore, these two mechanisms can be combined to increase capacity and reduce costs.Debido al aumento de la conectividad, la popularización de los servicios en la nube y el auge del Internet de las cosas (IoT), los enfoques descentralizados para la gestión de la confianza están cobrando impulso. Dado que las tecnologías de cadena de bloques (blockchain) proporcionan un archivo distribuido, están recibiendo una atención masiva por parte de la comunidad investigadora en diferentes campos de aplicación. Sin embargo, esta tecnología no proporciona ciberseguridad por sí misma. Por lo tanto, esta tesis tiene como primer objetivo proporcionar una revisión exhaustiva de las técnicas y elementos que se han propuesto para lograr la ciberseguridad en los sistemas basados en blockchain. Este análisis está dirigido a investigadores del área, especialistas en ciberseguridad y desarrolladores de blockchain. A su vez, se presentan una serie de lecciones aprendidas, siendo una de ellas el auge de Ethereum como una de las tecnologías más utilizadas. Asimismo, algunas características intrínsecas de la blockchain, como la disponibilidad permanente y la inmutabilidad, la hacen interesante para otros fines, concretamente como canal encubierto y con fines maliciosos. Por una parte, aún no se ha caracterizado el uso de la blockchain por parte de malwares. Por ello, esta tesis también analiza el actual estado del arte en este ámbito. Una de las lecciones aprendidas al analizar los datos es que las comunicaciones encubiertas han recibido poca atención. Por otro lado, aunque trabajos anteriores han analizado la viabilidad de los canales encubiertos en una tecnología blockchain concreta llamada Bitcoin, ningún trabajo anterior ha explorado el uso de Ethereum para establecer un canal encubierto considerando todos los campos de transacción y contratos inteligentes. Con el objetivo de fomentar una mayor investigación orientada a la defensa, en esta tesis se presentan dos mecanismos novedosos. En primer lugar, Zephyrus aprovecha todos los campos de Ethereum y el bytecode de los contratos inteligentes. En segundo lugar, Smart-Zephyrus complementa Zephyrus aprovechando los contratos inteligentes escritos en Solidity. Se evalúa, también, la viabilidad y el coste de ambos mecanismos. Los resultados muestran que Zephyrus, en el mejor de los casos, puede ocultar 40 Kbits en 0,57 s. por 1,64 US$, y recuperarlos en 2,8 s. Smart-Zephyrus, por su parte, es capaz de ocultar un secreto de 4 Kb en 41 s. Si bien es cierto que es caro (alrededor de 1,82 dólares por bit), el sigilo proporcionado podría valer la pena para los atacantes. Además, estos dos mecanismos pueden combinarse para aumentar la capacidad y reducir los costesPrograma de Doctorado en Ciencia y Tecnología Informática por la Universidad Carlos III de MadridPresidente: José Manuel Estévez Tapiador.- Secretario: Jorge Blasco Alís.- Vocal: Luis Hernández Encina

Building the Infrastructure for Cloud Security

Computer scienc

Data Protection for the Internet of Things

The Internet of Things (abbreviated: “IoT”) is acknowledged as one of the most important disruptive technologies with more than 16 billion devices forecasted to interact autonomously by 2020. The idea is simple, devices will help to measure the status of physical objects. The devices, containing sensors and actuators, are so small that they can be integrated or attached to any object in order to measure that object and possibly change its status accordingly. A process or work flow is then able to interact with those devices and to control the objects physically. The result is the collection of massive data in a ubiquitous form. This data can be analysed to gain new insights, a benefit propagated by the “Big Data” and “Smart Data” paradigms. While governments, cities and industries are heavily involved in the Internet of Things, society’s privacy awareness and the concerns over data protection in IoT increase steadily. The scale of the collection, processing and dissemination of possibly private information in the Internet of Things has long begun to raise privacy concerns. The problem is a fundamental one, it is the massive data collection that benefits the investment on IoT, while it contradicts the interest on data minimization coming from privacy advocates. And the challenges go even further, while privacy is an actively researched topic with a mature variety of privacy preserving mechanisms, legal studies and surveillance studies in specific contexts, investigations of how to apply this concepts in the constrained environment of IoT have merely begun. Thus the objective of this thesis is threefold and tackles several topics, looking at them in a differentiated way and later bringing them together for one of the first, (more) complete pictures of privacy in IoT. The first starting point is the throughout study of stakeholders, impact areas and proposals on an architectural reference model for IoT. At the time of this writing, IoT was adversed heavily by several companies, products and even governments, creating a blurred picture of what IoT really is. This thesis surveys stakeholders, scenarios, architecture paradigms and definitions to find a working definition for IoT which adequately describes the intersection between all of the aforementioned topics. In a further step, the definition is applied exemplary on two scenarios to identify the common building blocks of those scenarios and of IoT in general. The building blocks are then verified against a similar approach by the IoT-A and Rerum projects and unified to an IoT domain model. This approach purposefully uses notions and paradigms provided in related scientific work and European projects in order to benefit from existing efforts and to achieve a common understanding. In this thesis, the observation of so called cyber-physical properties of IoT leads to the conclusion that IoT proposals miss a core concept of physical interaction in the “real world”. Accordingly, this thesis takes a detour to jurisdiction and identifies ownership and possession as a main concept of “human-to-object” relationships. The analysis of IoT building blocks ends with an enhanced IoT domain model. The next step breaks down “privacy by design”. Notably hereby is that privacy by design has been well integrated in to the new European General Data Protection Regulation (GDPR). This regulation heavily affects IoT and thus serves as the main source of privacy requirements. Gürses et al.’s privacy paradigm (privacy as confidentiality, privacy as control and privacy as practice) is used for the breakdown, preceded by a survey of relevant privacy proposals, where relevancy was measured upon previously identified IoT impact areas and stakeholders. Independently from IoT, this thesis shows that privacy engineering is a task that still needs to be well understood. A privacy development lifecycle was therefore sketched as a first step in this direction. Existing privacy technologies are part of the survey. Current research is summed up to show that while many schemes exist, few are adequate for actual application in IoT due to their high energy or computational consumption and high implementation costs (most notably caused by the implementation of special arithmetics). In an effort to give a first direction on possible new privacy enhancing technologies for IoT, new technical schemes are presented, formally verified and evaluated. The proposals comprise schemes, among others, on relaxed integrity protection, privacy friendly authentication and authorization as well as geo-location privacy. The schemes are presented to industry partners with positive results. This technologies have thus been published in academia and as intellectual property items. This thesis concludes by bringing privacy and IoT together. The final result is a privacy enhanced IoT domain model accompanied by a set of assumptions regarding stakeholders, economic impacts, economic and technical constraints as well as formally verified and evaluated proof of concept technologies for privacy in IoT. There is justifiable interest in IoT as it helps to tackle many future challenges found in several impact areas. At the same time, IoT impacts the stakeholders that participate in those areas, creating the need for unification of IoT and privacy. This thesis shows that technical and economic constraints do not impede such a process, although the process has merely begun

Evidence-based Accountability Audits for Cloud Computing

Cloud computing is known for its on-demand service provisioning and has now become mainstream. Many businesses as well as individuals are using cloud services on a daily basis. There is a big variety of services that ranges from the provision of computing resources to services such as productivity suites and social networks. The nature of these services varies heavily in terms of what kind of information is being out-sourced to the cloud provider. Often, that data is sensitive, for instance when PII is being shared by an individual. Also, businesses that move (parts of) their processes to the cloud are actively participating in a major paradigm shift from having data on-premise to transfering data to a third-party provider. However, many new challenges come along with this trend, which are closely tied to the loss of control over data. When moving to the cloud, direct control over geographical storage location, who has access to it and how it is shared and processed is given up. Because of this loss of control, cloud customers have to trust cloud providers that they treat their data in an appropriate and responsible way. Cloud audits can be used to check how data has been processed in the cloud (i.e., by whom, for what purpose) and whether or not this happened in compliance with what has been defined in agreed-upon privacy and data storage, usage and maintenance (i.e., data handling) policies. This way, a cloud customer can regain some of the control he has given up by moving to the cloud. In this thesis, accountability audits are presented as a way to strengthen trust in cloud computing by providing assurance about the processing of data in the cloud according to data handling and privacy policies. In cloud accountability audits, various distributed evidence sources need to be considered. The research presented in this thesis discusses the use of various heterogeous evidence sources on all cloud layers. This way, a complete picture of the actual data handling practices that is based on hard facts can be presented to the cloud consumer. Furthermore, this strengthens transparency of data processing in the cloud, which can lead to improved trust in cloud providers, if they choose to adopt these mechanisms in order to assure their customers that their data is being handled according to their expectations. The system presented in this thesis enables continuous auditing of a cloud provider's adherence to data handling policies in an automated way that shortens audit intervals and that is based on evidence that is produced by cloud subsystems. An important aspect of many cloud offerings is the combination of multiple distinct cloud services that are offered by independent providers. Data is thereby freuqently exchanged between the cloud providers. This also includes trans-border flows of data, where one provider may be required to adhere to more strict data protection requirements than the others. The system presented in this thesis addresses such scenarios by enabling the collection of evidence at providers and evaluating it during audits. Securing evidence quickly becomes a challenge in the system design, when information that is needed for the audit is deemed sensitive or confidential. This means that securing the evidence at-rest as well as in-transit is of utmost importance, in order not to introduce a new liability by building an insecure data heap. This research presents the identification of security and privacy protection requirements alongside proposed solutions that enable the development of an architecture for secure, automated, policy-driven and evidence-based accountability audits

Best Practices and Recommendations for Cybersecurity Service Providers

This chapter outlines some concrete best practices and recommendations for cybersecurity service providers, with a focus on data sharing, data protection and penetration testing. Based on a brief outline of dilemmas that cybersecurity service providers may experience in their daily operations, it discusses data handling policies and practices of cybersecurity vendors along the following five topics: customer data handling; information about breaches; threat intelligence; vulnerability-related information; and data involved when collaborating with peers, CERTs, cybersecurity research groups, etc. There is, furthermore, a discussion of specific issues of penetration testing such as customer recruitment and execution as well as the supervision and governance of penetration testing. The chapter closes with some general recommendations regarding improving the ethical decision-making procedures of private cybersecurity service providers

Ethical and Unethical Hacking

The goal of this chapter is to provide a conceptual analysis of ethical, comprising history, common usage and the attempt to provide a systematic classification that is both compatible with common usage and normatively adequate. Subsequently, the article identifies a tension between common usage and a normativelyadequate nomenclature. ‘Ethical hackers’ are often identified with hackers that abide to a code of ethics privileging business-friendly values. However, there is no guarantee that respecting such values is always compatible with the all-things-considered morally best act. It is recognised, however, that in terms of assessment, it may be quite difficult to determine who is an ethical hacker in the ‘all things considered’ sense, while society may agree more easily on the determination of who is one in the ‘business-friendly’ limited sense. The article concludes by suggesting a pragmatic best-practice approach for characterising ethical hacking, which reaches beyond business-friendly values and helps in the taking of decisions that are respectful of the hackers’ individual ethics in morally debatable, grey zones