Mälardalen University Press Licentiate Theses No. 157 SECURE SERVICE PROVISIONING IN A PUBLIC CLOUD Mudassar Aslam 2012 School of Innovation, Design and Engineering Copyright © Mudassar Aslam, 2012 ISBN 978-91-7485-081-9 ISSN 1651-9256 Printed by Mälardalen University, Västerås, Sweden Populärvetenskaplig sammanfattning Utvecklingen av molntekniker möjliggör utnyttjande av IT-resurser över Internet, och kan innebära många fördelar för såväl företag som privat- personer. Dock innebär denna nya modell för användandet av resurser att säkerhetsfrågor uppstår, frågor som inte existerat i traditionell resur- shantering på datorer. I avhandlingen fokuserar vi på säkerhetsfrågor som rör en användare av molntjänster (t.ex. en organisation, myndighet etc.), när användaren vill leasa molntjänster i form av Virtuella maskiner (VM) från en publik leverantör av Infrastructure-as-a-Service (IaaS). Det finns många säkerhetsområden i molnsystem: att hålla data hemliga, att resurserna är korrekta, att servicen är den utlovade, att säkerheten kan kontrolleras, etc. I denna avhandling fokuserar vi på säkerhetsproblem som resulterar i att tillit saknas mellan aktörerna i molnsystem, och som därmed hindrar säkerhetskänsliga användare från att använda molntjänster. Från en behovsanalys ur säkerhetsperspektiv föreslår vi lösningar som möjliggör tillit i publika IaaS-moln. Våra lösningar rör i huvudsak säker livscykelhantering av virtuella maskiner, inklusive mekanismer för säker start och säker migrering av virtuella maskiner. Lösningarna säkerställer att användarens VM alltid är skyddad i molnet genom att den endast tillåts exekveras på pål- itliga (trusted) plattformar. Detta sker genom att använda tekniker för s.k. trusted computing (pålitlig datoranvändning), vilket innebär att användaren på distans kan kontrollera om plattformen är tillförlitlig eller inte. Vi presenterar även en prototypimplementation som visar re- aliserbarheten av de föreslagna säkerhetsprinciperna för säker start och migrering av VM. i Abstract The evolution of cloud technologies which allows the provisioning of IT resources over the Internet promises many benefits for the individuals and enterprises alike. However, this new resource provisioning model comes with the security challenges which did not exist in the traditional resource procurement mechanisms. We focus on the possible security concerns of a cloud user (e.g. an organization, government department, etc.) to lease cloud services such as resources in the form of Virtual Ma- chines (VM) from a public Infrastructure-as-a-Service (IaaS) provider. There are many security critical areas in the cloud systems, such as data confidentiality, resource integrity, service compliance, security audits etc. In this thesis, we focus on the security aspects which result in the trust deficit among the cloud stakeholders and hence hinder a security sensi- tive user to benefit from the opportunities offered by the cloud comput- ing. Based upon our findings from the security requirements analysis, we propose solutions that enable user trust in the public IaaS clouds. Our solutions mainly deal with the secure life cycle management of the user VM which include mechanisms for VM launch and migration. The VM launch and migration solutions ensure that the user VM is always protected in the cloud by only allowing it to run on the user trusted plat- forms. This is done by using trusted computing techniques that allow the users to remotely attest and hence rate the cloud platforms trusted or untrusted. We also provide a prototype implementation to prove the implementation feasibility of the proposed trust enabling principles used in the VM launch and migration solutions. iii Acknowledgments First of all, I am really thankful to my Allah who gave me perseverance, knowledge and strength to achieve this milestone. I pray Him to make my knowledge beneficial for others. I am grateful to all people in SICS, MDH and Ericsson who sup- ported and guided me in doing this work; especially, my co-supervisor Dr. Christian Gehrmann who provided me the opportunity to work in an esteemed research environment at SICS. I am indebted to all the efforts and valuable time that Christian has spent on me for guiding, improv- ing and polishing my research skills right from the very first day. I also want to express my sincere regards and gratitude for my main supervi- sor Prof. Mats Björkman who provided me the much needed motivation, inspiration and guidance in achieving this milestone. I feel happy, satisfied and proud to get the opportunity to work with the learned researchers from SICS and Ericsson who provided very useful feedback to improve my work and tune it according to the current and future industrial demands. I express my gratitude to András Méhes who provided his insightful criticism to remove the lacunae in various stages of this work; Lars Rasmusson, Fredric Morenius and Nicolae Paladi for their collaborative research and development activities; and Rolf Blom for his useful research directions. I am really thankful to all my co-workers specially Anders Gunnar, Anders Lindgren, Bengt Ahlgren, Björn Grönvall, Henrik Abrahamsson, Ian Marsh, Laura Feeney and Maria Holm who provided a unique profes- sional and research environment for me. I would specially like to thank Oliver Schwarz for his discussions (technical and social) and valuable suggestions whenever solicited. Finally, I would like to thank all my friends and colleagues including Shahid Raza, Shahzad Saleem, Zeeshan Ali Shah and many others who helped me whenever required. v vi I would like to dedicate this work to my parents and family who supported me throughout my academic and professional carrier with their love, guidance and sacrifices whenever required. Mudassar Aslam Stockholm, October, 2012 This work has been performed in the Secure Systems Group (SecSys) which is a security group within Communication Networks and Systems laboratory (NETS) in the Swedish Institute of Computer Science (SICS). Other partners that were involved in various projects include Ericsson, Saab, TeliaSonera and T2Data. The funding for this work has mainly been provided by VINNOVA through different research projects, and also by the Higher Education Commis- sion (HEC), Pakistan in the form of scholarship grant for my PhD studies. The SICS is jointly sponsored by the Swedish government and the Industry partners which include TeliaSonera, Ericsson, Saab AB, FMV (Defense Ma- teriel Administration), Green Cargo (Swedish freight railway operator), ABB, and Bombardier Transportation. List of Publications Papers Included in the Licentiate Thesis1 Paper A Security Considerations for Virtual Platform Provisioning. Mudassar Aslam, Christian Gehrmann. In European Conference on Information Warfare and Security ECIW-2011, 7-8 July 2011, Tallin, Estonia. Paper B Securely Launching Virtual Machines on Trustworthy Plat- forms in a Public Cloud. Mudassar Aslam, Christian Gehrmann, Lars Rasmusson, Mats Björkman. In 2nd International Conference on Cloud Comput- ing and Services Science, CLOSER 2012, 18-21 April 2012, Porto, Portugal. Paper C Security and Trust Preserving VM Migrations in Public Clouds. Mudassar Aslam, Christian Gehrmann, Mats Björkman. In 2nd IEEE International Symposium on Trust and Security in Cloud Computing, part of IEEE TrustCom-12, 25-27 June 2012, Liver- pool, UK. Paper D Protecting Private Data in the Cloud. Lars Rasmusson, Mudassar Aslam. In 2nd International Con- ference on Cloud Computing and Services Science, CLOSER 2012, 18-21 April 2012, Porto, Portugal. 1The included articles have been reformatted to comply with the thesis layout vii viii SICS Technical Reports • Mudassar Aslam, Christian Gehrmann. TCG Based Approach for Secure Management of Virtualized Platforms: state-of-the-art. ISSN No. 1100-3154, SICS Technical Report (T2010:05), 2010. Available at http://soda.swedish-ict.se/3993/ • Mudassar Aslam, Christian Gehrmann. Deploying Virtual Ma- chines on Shared Platforms. ISSN No. 1100-3154, SICS Technical Report (T2011:07), 2011. Available at http://soda.swedish-ict. se/4170/ List of Acronyms AIK Attestation Identity Key CAP EX Capital Expenditure Client See User CSA Cloud Security Alliance CSP Cloud Service Provider EK Endorsement Key GuestOS Guest Operating System IaaS Infrastructure-as-a-Service P aaS Platform-as-a-Service PCA Privacy CA PCR Platform Configuration Registers P rovider Cloud Service Provider P T AA Platform Trust Assurance Authority SaaS Software-as-a-Service SecaaS Security-as-a-Service SLA Service Level Agreement SRK Storage Root Key ix x T AL Trust Assurance Level TCG Trusted Computing Group TPM Trusted Platform Module TSPI TCG Service Provider Interface TSS TCG Software Stack User Cloud Service User VMM Virtual Machine Monitor Contents I Thesis 1 1 Introduction 3 1.1 Contributions ......................... 4 1.2 Thesis Outline ........................ 6 2 Background 7 2.1 Virtualization ......................... 7 2.1.1 The XEN Hypervisor ................ 8 2.2 Cloud Computing ....................... 9 2.2.1 Service Models .................... 10 2.2.2 Deployment Models ................. 12 2.3 Introducing Digital Trust .................. 14 2.3.1 The Trusted Computing Group (TCG) ....... 14 2.3.2 Trusted Platform Module (TPM) .......... 15 2.3.3 TPM - Key Management .............. 15 2.3.4 TPM Message Protection .............. 17 2.3.5 Sealing Data Remotely ................ 19 3 Security Critical Areas in Cloud Computing 21 3.1 Security Assessment of the Host Platform ......... 22 3.1.1