Composite Enclaves: Towards Disaggregated Trusted Execution

The ever-rising computation demand is forcing the move from the CPU to heterogeneous specialized hardware, which is readily available across modern datacenters through disaggregated infrastructure. On the other hand, trusted execution environments (TEEs), one of the most promising recent developments in hardware security, can only protect code confined in the CPU, limiting TEEs' potential and applicability to a handful of applications. We observe that the TEEs' hardware trusted computing base (TCB) is fixed at design time, which in practice leads to using untrusted software to employ peripherals in TEEs. Based on this observation, we propose \emph{composite enclaves} with a configurable hardware and software TCB, allowing enclaves access to multiple computing and IO resources. Finally, we present two case studies of composite enclaves: i) an FPGA platform based on RISC-V Keystone connected to emulated peripherals and sensors, and ii) a large-scale accelerator. These case studies showcase a flexible but small TCB (2.5 KLoC for IO peripherals and drivers), with a low-performance overhead (only around 220 additional cycles for a context switch), thus demonstrating the feasibility of our approach and showing that it can work with a wide range of specialized hardware

Cyber-Storms Come from Clouds: Security of Cloud Computing in the IoT Era

The Internet of Things (IoT) is rapidly changing our society to a world where every "thing" is connected to the Internet, making computing pervasive like never before. This tsunami of connectivity and data collection relies more and more on the Cloud, where data analytics and intelligence actually reside. Cloud computing has indeed revolutionized the way computational resources and services can be used and accessed, implementing the concept of utility computing whose advantages are undeniable for every business. However, despite the benefits in terms of flexibility, economic savings, and support of new services, its widespread adoption is hindered by the security issues arising with its usage. From a security perspective, the technological revolution introduced by IoT and Cloud computing can represent a disaster, as each object might become inherently remotely hackable and, as a consequence, controllable by malicious actors. While the literature mostly focuses on security of IoT and Cloud computing as separate entities, in this article we provide an up-to-date and well-structured survey of the security issues of Cloud computing in the IoT era. We give a clear picture of where security issues occur and what their potential impact is. As a result, we claim that it is not enough to secure IoT devices, as cyber-storms come from Clouds

Side Channels in the Cloud: Isolation Challenges, Attacks, and Countermeasures

Cloud computing is based on the sharing of physical resources among several virtual machines through a virtualization layer providing software isolation. Despite advances in virtualization, data security and isolation guarantees remain important challenges for cloud providers. Some of the most prominent isolation violations come from side-channel attacks that aim at exploiting and using a leaky channel to obtain sensitive data such as encryption keys. Such channels may be created by vulnerable implementations of cryptographic algorithms, exploiting weaknesses of processor architectures or of resource sharing in the virtualization layer. In this paper, we provide a comprehensive survey of side-channel attacks (SCA) and mitigation techniques for virtualized environments, focusing on cache-based attacks. We review isolation challenges, attack classes and techniques. We also provide a layer-based taxonomy of applicable countermeasures , from the hardware to the application level, with an assessment of their effectiveness

Cyber-storms come from clouds:Security of cloud computing in the IoT era

The Internet of Things (IoT) is rapidly changing our society to a world where every “thing” is connected to the Internet, making computing pervasive like never before. This tsunami of connectivity and data collection relies more and more on the Cloud, where data analytics and intelligence actually reside. Cloud computing has indeed revolutionized the way computational resources and services can be used and accessed, implementing the concept of utility computing whose advantages are undeniable for every business. However, despite the benefits in terms of flexibility, economic savings, and support of new services, its widespread adoption is hindered by the security issues arising with its usage. From a security perspective, the technological revolution introduced by IoT and Cloud computing can represent a disaster, as each object might become inherently remotely hackable and, as a consequence, controllable by malicious actors. While the literature mostly focuses on the security of IoT and Cloud computing as separate entities, in this article we provide an up-to-date and well-structured survey of the security issues of cloud computing in the IoT era. We give a clear picture of where security issues occur and what their potential impact is. As a result, we claim that it is not enough to secure IoT devices, as cyber-storms come from Clouds

Segurança em virtualização VMware: Infraestruturas e agregados de máquinas virtuais

Segurança em Infraestruturas e Agregados de Máquinas Virtuais A Proteção de ambientes virtuais Virtualização é uma tecnologia que utiliza um ambiente lógico para superar as limitações físicas do hardware. Devido ás suas características de encapsulamento e isolamento a virtualização é a base para o paradigma da computação em nuvem 1. Os diversos tipos das tecnologias de virtualização, implicações de segurança e sistemas de ficheiros em infraestruturas VMware serão apresentadas ao longo da obra. A virtualização é uma tecnologia complexa, com muitas facetas e inúmeros tipos de controlos, que podem ser implementados para proteger os ativos virtuais bem como as suas máquinas hospedeiras. ”Virtualization is both an opportunity and a threat” diz Patrick Lin director de produto da VMware [1]. Os sistemas operativos atuais fornecem uma abstração de processos para alcançar uma partilha de recursos e isolamento, no entanto a partir de uma perspetiva de segurança, um intruso que comprometa um processo, pode ganhar controlo total sobre o sistema. Isso faz com que os sistemas de segurança que se encontram em execução no mesmo sistema, tais como programas de antivírus ou sistemas de deteção de intrusão, poderão se encontrar também vulneráveis a ataques. Em resposta ao isolamento imperfeito entre processos, pode-se recorrer á utilização de agregados virtuais com o intuito de garantir a privacidade e a confidencialidade e integridade das informações. Será apresentada uma análise pormenorizada das estratégias de ataque que podem ser usadas contra as infraestruturas de virtualização VMware, bem como o seu nível de eficácia

Game-Theoretic Frameworks and Strategies for Defense Against Network Jamming and Collocation Attacks

Modern networks are becoming increasingly more complex, heterogeneous, and densely connected. While more diverse services are enabled to an ever-increasing number of users through ubiquitous networking and pervasive computing, several important challenges have emerged. For example, densely connected networks are prone to higher levels of interference, which makes them more vulnerable to jamming attacks. Also, the utilization of software-based protocols to perform routing, load balancing and power management functions in Software-Defined Networks gives rise to more vulnerabilities that could be exploited by malicious users and adversaries. Moreover, the increased reliance on cloud computing services due to a growing demand for communication and computation resources poses formidable security challenges due to the shared nature and virtualization of cloud computing. In this thesis, we study two types of attacks: jamming attacks on wireless networks and side-channel attacks on cloud computing servers. The former attacks disrupt the natural network operation by exploiting the static topology and dynamic channel assignment in wireless networks, while the latter attacks seek to gain access to unauthorized data by co-residing with target virtual machines (VMs) on the same physical node in a cloud server. In both attacks, the adversary faces a static attack surface and achieves her illegitimate goal by exploiting a stationary aspect of the network functionality. Hence, this dissertation proposes and develops counter approaches to both attacks using moving target defense strategies. We study the strategic interactions between the adversary and the network administrator within a game-theoretic framework. First, in the context of jamming attacks, we present and analyze a game-theoretic formulation between the adversary and the network defender. In this problem, the attack surface is the network connectivity (the static topology) as the adversary jams a subset of nodes to increase the level of interference in the network. On the other side, the defender makes judicious adjustments of the transmission footprint of the various nodes, thereby continuously adapting the underlying network topology to reduce the impact of the attack. The defender\u27s strategy is based on playing Nash equilibrium strategies securing a worst-case network utility. Moreover, scalable decomposition-based approaches are developed yielding a scalable defense strategy whose performance closely approaches that of the non-decomposed game for large-scale and dense networks. We study a class of games considering discrete as well as continuous power levels. In the second problem, we consider multi-tenant clouds, where a number of VMs are typically collocated on the same physical machine to optimize performance and power consumption and maximize profit. This increases the risk of a malicious virtual machine performing side-channel attacks and leaking sensitive information from neighboring VMs. The attack surface, in this case, is the static residency of VMs on a set of physical nodes, hence we develop a timed migration defense approach. Specifically, we analyze a timing game in which the cloud provider decides when to migrate a VM to a different physical machine to mitigate the risk of being compromised by a collocated malicious VM. The adversary decides the rate at which she launches new VMs to collocate with the victim VMs. Our formulation captures a data leakage model in which the cost incurred by the cloud provider depends on the duration of collocation with malicious VMs. It also captures costs incurred by the adversary in launching new VMs and by the defender in migrating VMs. We establish sufficient conditions for the existence of Nash equilibria for general cost functions, as well as for specific instantiations, and characterize the best response for both players. Furthermore, we extend our model to characterize its impact on the attacker\u27s payoff when the cloud utilizes intrusion detection systems that detect side-channel attacks. Our theoretical findings are corroborated with extensive numerical results in various settings as well as a proof-of-concept implementation in a realistic cloud setting