Privacy in cloud computing

Tese de mestrado em Segurança Informática, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2010O paradigma cloud computing está progressivamente a integrar-se nas tecnologias de informação e é também visto por muitos como a próxima grande viragem na indústria da computação. A sua integração significa grandes alterações no modo como olhamos para a segurança dos dados de empresas que decidem confiar informação confidencial aos fornecedores de serviços cloud. Esta alteração implica um nível muito elevado de confiança no fornecedor do serviço. Ao mudar para a cloud, uma empresa relega para o fornecedor do serviço controlo sobre os seus dados, porque estes vão executar em hardware que é propriedade do fornecedor e sobre o qual a empresa não tem qualquer controlo. Este facto irá pesar muito na decisão, de mudar para a cloud, de empresas que tratam informação delicada (p.ex., informação médica ou financeira). Neste trabalho propomos demonstrar de que forma um administrador malicioso, com acesso ao hardware do fornecedor, consegue violar a privacidade dos dados que o utilizador da cloud confiou ao prestador desses serviços. Definimos como objectivo uma análise detalhada de estratégias de ataque que poderão ajudar um administrador malicioso a quebrar a privacidade de clientes da cloud, bem como a eficácia demonstrada contra esses mesmos ataques por mecanismos de protecção já propostos para a cloud. Pretendemos que este trabalho seja capaz de alertar a comunidade científica para a gravidade dos problemas de segurança que actualmente existem na cloud e, que ao mesmo tempo, sirva como motivação para uma acção célere desta, de forma a encontrar soluções para esses problemas.The paradigm of cloud computing is progressively integrating itself in the Information Technology industry and it is also seen by many experts as the next big shift in this industry. This integration implies considerable alterations in the security schemes used to ensure that the privacy of confidential information, companies entrust to the cloud provider, is kept. It also means that the level of trust in the cloud provider must be considerably high. When moving to the cloud, a company relinquishes control over its data to the cloud provider. This happens because, when operating in the cloud, the data is going to execute on top of the hardware owned by the cloud provider and, in this scenario, the client has no control over that hardware. Companies that deal with sensitive data (e.g., medical or financial records) have to weigh the importance of this problem when considering moving their data to the cloud. In this work, we provide a demonstration of how a malicious administrator, with access to the hardware of the cloud provider, is capable of violating the privacy of the data entrusted to the cloud provider by his clients. Our objective is to offer a detailed analysis of attack strategies that can be used by a malicious administrator to break the privacy of cloud clients, as well as the level of efficacy demonstrated by some protection mechanism that have already been proposed for the cloud. We also hope that this work is capable of capturing the attention of the research community to the security problems existent in the cloud and, that at the same time, it works as a motivation factor for a prompt action in order to find solutions for these problems

Insider threat : memory confidentiality and integrity in the cloud

PhD ThesisThe advantages of always available services, such as remote device backup or data storage, have helped the widespread adoption of cloud computing. However, cloud computing services challenge the traditional boundary between trusted inside and untrusted outside. A consumer’s data and applications are no longer in premises, fundamentally changing the scope of an insider threat. This thesis looks at the security risks associated with an insider threat. Specifically, we look into the critical challenge of assuring data confidentiality and integrity for the execution of arbitrary software in a consumer’s virtual machine. The problem arises from having multiple virtual machines sharing hardware resources in the same physical host, while an administrator is granted elevated privileges over such host. We used an empirical approach to collect evidence of the existence of this security problem and implemented a prototype of a novel prevention mechanism for such a problem. Finally, we propose a trustworthy cloud architecture which uses the security properties our prevention mechanism guarantees as a building block. To collect the evidence required to demonstrate how an insider threat can become a security problem to a cloud computing infrastructure, we performed a set of attacks targeting the three most commonly used virtualization software solutions. These attacks attempt to compromise data confidentiality and integrity of cloud consumers’ data. The prototype to evaluate our novel prevention mechanism was implemented in the Xen hypervisor and tested against known attacks. The prototype we implemented focuses on applying restrictions to the permissive memory access model currently in use in the most relevant virtualization software solutions. We envision the use of a mandatory memory access control model in the virtualization software. This model enforces the principle of least privilege to memory access, which means cloud administrators are assigned with only enough privileges to successfully perform their administrative tasks. Although the changes we suggest to the virtualization layer make it more restrictive, our solution is versatile enough to port all the functionality available in current virtualization viii solutions. Therefore, our trustworthy cloud architecture guarantees data confidentiality and integrity and achieves a more transparent trustworthy cloud ecosystem while preserving functionality. Our results show that a malicious insider can compromise security sensitive data in the three most important commercial virtualization software solutions. These virtualization solutions are publicly available and the number of cloud servers using these solutions accounts for the majority of the virtualization market. The prevention mechanism prototype we designed and implemented guarantees data confidentiality and integrity against such attacks and reduces the trusted computing base of the virtualization layer. These results indicate how current virtualization solutions need to reconsider their view on insider threats