Trusted Computer System Evaluation Criteria
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Trusted System Concepts
Trusted System Concepts Trusted System Concepts Marshall D. Abrams, Ph.D. Michael V. Joyce The MITRE Corporation 7525 Colshire Drive McLean, VA 22102 703-883-6938 [email protected] This is the first of three related papers exploring how contemporary computer architecture affects security. Key issues in this changing environment, such as distributed systems and the need to support multiple access control policies, necessitates a generalization of the Trusted Computing Base paradigm. This paper develops a conceptual framework with which to address the implications of the growing reliance on Policy-Enforcing Applications in distributed environments. 1 INTRODUCTION A significant evolution in computer software architecture has taken place over the last quarter century. The centralized time-sharing systems of the 1970s and early 1980s are rapidly being superseded by the distributed architectures of the 1990s. As an integral part of the architecture evolution, the composition of the system access control policy has changed. Instead of a single policy, the system access control policy is more likely to be a composite of several constituent policies implemented in applications that create objects and enforce their own unique access control policies. This paper first provides a survey that explains how the security community developed the accepted concepts and criteria that addressed the time-shared architectures. Second, the paper focuses on the changes currently ongoing, providing insight into the driving forces and probable directions. This paper presents contemporary thinking; it summarizes and generalizes vertical and horizontal extensions to the Trusted Computing Base (TCB) concept. While attempting to be logical and rigorous, formalism is avoided. This paper was first published in Computers & Security, Vol. -
Inspecting Data from the Safety of Your Trusted Execution Environment
Inspecting data from the safety of your trusted execution environment John Williams johnwwil [at] u.washington.edu June, 2015 Abstract: This paper presents a proof of concept that uses ARM TrustZone to perform introspection of a Linux kernel running in the normal world from within a secure-world system. Techniques from existing volatile-memory analysis applications are repurposed for application in real-time through asynchronous introspection of the normal world. The solution presented here leverages open-source software that is actively being developed to support additional architectures. 1 INTRODUCTION As technology becomes more prevalent in our day-to-day lives, we increasingly rely on mobile devices for both business and personal purposes. Emerging security threats, such as rootkits that can scan memory for protected PCI information, have been responsible for large-scale breaches. It has been predicted that targeted exploit kits and attack services will soon exist for mobile platforms, which could enable the exploitation of mobile devices on an unprecedented scale [1]. Techniques for mitigating such threats to mobile devices have largely evolved in parallel with industry demand for them. While some companies have indeed made progress through continued addition of product features that increase the security of devices, other companies have simply pivoted their marketing efforts to emphasize or recast certain aspects of their existing capabilities. In order to select the right products and features for protecting sensitive data and activities, effective segmentation is key. While segmentation within devices has traditionally been implemented at the operating system level, in recent years architectural modification at the chip level has emerged as a way to provide hard segmentation between execution environments. -
Leveraging ARM Trustzone and Verifiable Computing to Provide Auditable Mobile Functions Nuno O
Leveraging ARM TrustZone and Verifiable Computing to Provide Auditable Mobile Functions Nuno O. Duarte Sileshi Demesie Yalew INESC-ID / IST, University of Lisbon KTH Royal Institute of Technology [email protected] [email protected] Nuno Santos Miguel Correia INESC-ID / IST, University of Lisbon INESC-ID / IST, University of Lisbon [email protected] [email protected] ABSTRACT 1 INTRODUCTION The increase of personal data on mobile devices has been fol- For over 30 years [5], an important problem that has fasci- lowed by legislation that forces service providers to process nated the research community is about trusting the result of and maintain users’ data under strict data protection policies. computations performed on untrusted platforms. Since the In this paper, we propose a new primitive for mobile applica- advent of cloud computing, this interest has further grown tions called auditable mobile function (AMF) to help service in obtaining proofs of code execution on untrusted clouds. providers enforcing such policies by enabling them to process An approach to address this problem that has garnered sensitive data within users’ devices and collecting proofs of particular attention is verifiable computing. At a high-level, function execution integrity. We present SafeChecker, a com- verifiable computing consists of studying how a prover can putation verification system that provides mobile application convince a verifier of a mathematical assertion. The main support for AMFs, and evaluate the practicality of different obstacle faced by this field has been practicality, as the costs usage scenario AMFs on TrustZone-enabled hardware. of computing and verifying proofs over general computa- tions tend to be very high [21]. -
Trusted Computing Serving an Anonymity Service
Trusted Computing Serving an Anonymity Service Alexander Böttcher Bernhard Kauer Hermann Härtig Technische Universität Dresden Department of Computer Science Operating Systems Group {boettcher, kauer, haertig}@os.inf.tu-dresden.de Abstract [15] in the authors’ group, will show. An unknown crim- inal to be investigated was supposed to use an anonymity We leveraged trusted computing technology to service. The police and later on the German Federal Bu- counteract certain insider attacks. Furthermore, we reau of Criminal Investigation (FBCI) required to investi- show with one of the rare server based scenarios that gate a criminal that uses a known URL. In order to enable an anonymity service can profit from trusted comput- criminal prosecution by a given warrant the software was ing. We based our design on the Nizza Architecture extended to log connection data [6, 5]. This function of [14] with its small kernel and minimal multi-server the anonymity software [3] was used only with a warrant OS. We even avoided Nizza’s legacy container and but without directly notifying the users. After the warrant got a much smaller, robust and hopefully more secure was reversed the FBCI showed up with a delivery warrant system, since we believe that minimizing the trusted for a log record (which were later on reversed illegal [4]), computing base is an essential requirement for trust first at the institute and later on at the institute’s directors into software. private home. This incident shows a whole class of attacks on the 1 Introduction anonymity and more general every computing service. Vendor and providers under constraint can reveal the ser- Anonymity while using the Internet is widely considered vice because of insider knowledge and physical access a legitimate and - for many use cases - essential require- to those services. -
The Nizza Secure-System Architecture
Appears in the proceedings of CollaborateCom 2005, San Jose, CA, USA The Nizza Secure-System Architecture Hermann Härtig Michael Hohmuth Norman Feske Christian Helmuth Adam Lackorzynski Frank Mehnert Michael Peter Technische Universität Dresden Institute for System Architecture D-01062 Dresden, Germany [email protected] Abstract rely on a standard OS (including the kernel) to assure their security properties. The trusted computing bases (TCBs) of applications run- To address the conflicting requirements of complete ning on today’s commodity operating systems have become functionality and the protection of security-sensitive data, extremely large. This paper presents an architecture that researchers have devised system architectures that reduce allows to build applications with a much smaller TCB. It the system’s TCB by running kernels in untrusted mode is based on a kernelized architecture and on the reuse of in a secure compartment on top of a small security kernel; legacy software using trusted wrappers. We discuss the de- security-sensitive services run alongside the OS in isolated sign principles, the architecture and some components, and compartments of their own. This architecture is widely re- a number of usage examples. ferred to as kernelized standard OS or kernelized system. In this paper, we describe Nizza, a new kernelized- system architecture. In the design of Nizza, we set out to answer the question of how small the TCB can be made. 1 Introduction We have argued in previous work that the (hardware and software) technologies needed to build small secure-system Desktop and hand-held computers are used for many platforms have become much more mature since earlier at- functions, often in parallel, some of which are security tempts [8]. -
Reducing TCB Size by Using Untrusted Components — Small Kernels Versus Virtual-Machine Monitors
To be published in Proceedings of the 11th ACM SIGOPS European Workshop, Leuven, Belgium, 2004 Reducing TCB size by using untrusted components — small kernels versus virtual-machine monitors Michael Hohmuth Michael Peter Hermann Hartig¨ Jonathan S. Shapiro Technische Universitat¨ Dresden Johns Hopkins University Department of Computer Science Department of Computer Science Operating Systems Group Systems Research Laboratory hohmuth,peter,haertig ¡ @os.inf.tu-dresden.de [email protected] Abstract tems, such as message passing and memory sharing, the overall size of the TCB (which includes all components an Secure systems are best built on top of a small trusted oper- application relies on) can actually be reduced for a large class ating system: The smaller the operating system, the easier it of applications. can be assured or verified for correctness. Another assumption we address in this paper is that all In this paper, we oppose the view that virtual-machine components on which an application has operational depen- monitors (VMMs) are the smallest systems that provide se- dencies must be in this application’s TCB. This presumption cure isolation because they have been specifically designed leads to the unnecessary inclusion of many (protocol and de- to provide little more than this property. The problem with vice) drivers into the TCB. this assertion is that VMMs typically do not support inter- The basic idea for reducing TCB size is to extract sys- process communication, complicating the use of untrusted tem components from the TCB and consider them as un- components inside a secure systems. trusted without violating the security requirements of user We propose extending traditional VMMs with features for applications. -
Secure Bootstrap Is Not Enough: Shoring up the Trusted Computing Base James Hendricks Leendert Van Doorn Carnegie Mellon University IBM T.J
Proceedings of the Eleventh SIGOPS European Workshop, ACM SIGOPS, Leuven, Belgium, September 2004. Secure Bootstrap is Not Enough: Shoring up the Trusted Computing Base James Hendricks Leendert van Doorn Carnegie Mellon University IBM T.J. Watson Research Center 5000 Forbes Ave 19 Skyline Drive Pittsburgh, PA Hawthorne, NY [email protected] [email protected] Abstract for each bootstrap step before it is executed. For exam- We propose augmenting secure boot with a mechanism ple, the BIOS could verify a public-key signature of the to protect against compromises to field-upgradeable de- disk’s boot sector to ensure its authenticity; the boot sector vices. In particular, secure boot standards should verify could then verify the public-key signature of the OS boot- the firmware of all devices in the computer, not just de- strap code, which could likewise verify the privileged OS vices that are accessible by the host CPU. Modern comput- processes and drivers. Though such an approach would ob- ers contain many autonomous processing elements, such viously not guarantee the security of the OS code, it would as disk controllers, disks, network adapters, and coproces- at least guarantee the authenticity. sors, that all have field-upgradeable firmware and are an A weakness to this approach is that the BIOS in most essential component of the computer system’s trust model. personal computers is writable. One solution is to store Ignoring these devices opens the system to attacks similar the BIOS on a ROM. However, a ROM-based approach to those secure boot was engineered to defeat. -
Trusted Computing Base
Microkernels and L4 Introduction COMP9242 2006/S2 Week 1 cse/UNSW/NICTA WHY MICROKERNELS? MONOLITHIC KERNEL WHY MICROKERNELS? MONOLITHIC KERNEL: • Kernel has access to everything § all optimisations possible § all techniques/mechanisms/concepts implementable WHY MICROKERNELS? MONOLITHIC KERNEL: • Kernel has access to everything § all optimisations possible § all techniques/mechanisms/concepts implementable • Can be extended by simply adding code WHY MICROKERNELS? MONOLITHIC KERNEL: • Kernel has access to everything § all optimisations possible § all techniques/mechanisms/concepts implementable • Can be extended by simply adding code • Cost: Complexity § growing size § limited maintainability cse/UNSW/NICTA COMP9242 2006/S2 W1 P1 MICROKERNEL:IDEA • Small kernel providing core functionality § only code running in privileged mode • Most OS services provided by user-level servers • Applications communicate with servers via message-passing IPC Application syscall user mode VFS IPC, file system Application UNIX Device File Server Driver Server Scheduler, virtual memory kernel IPC mode Device drivers, Dispatcher, ... IPC, virtual memory Hardware Hardware cse/UNSW/NICTA COMP9242 2006/S2 W1 P2 TRUSTED COMPUTING BASE The part of the system which must be trusted to operate correctly TRUSTED COMPUTING BASE The part of the system which must be trusted to operate correctly Application Service Hardware System: traditional embedded TRUSTED COMPUTING BASE The part of the system which must be trusted to operate correctly Application Service Hardware System: -
TC) and Next Generation Secured Computing Base (NGSCB
Trusted Computing (TC) and Next Generation Secured Computing Base (NGSCB) “For years, Bill Gate has dreamed of finding a way to make the Chinese pay for software: TC looks like being the answer to his prayer.” – Ross Anderson [Reference 7] The Trusted Computing (TC) and Next Generation Secured Computing Base (NGSCB) Version 1.0 Spring 2005 Computer Networking Management By: Jianji (Joseph) Yu Jeffrey Khuu Joseph Yu and Jeffrey Khuu Computer Network Management Page 1 of 10 Trusted Computing (TC) and Next Generation Secured Computing Base (NGSCB) Table of Contents 1. Introduction ……………………………………………………………3 Overview 1.1 The Trusted Computing: Trusted Computing Base (TCB) And Trusted Computing Group (TCG) …………………………3 1.2 Next Generation Secured Computing Base (NGSCB) ......…4 2. NGSCB ……………………………………………………………....….5 2.1 Features 2.1.1 Two operating environments ….............………………….…..5 2.1.2 Four features of NGSCB …..……………......………....…...5 2.2 Architecture 2.2.1 Two primary system components in Trusted operating environment ………………...….6 2.2.2 Nexus …………...……………………………………………..7 2.2.3 NCA …………………………..……......…………………………. 7 2.3 NGSCB Summary …………...………….......…………………….8 3. Analysis of NGSCB ……………………………………………9 3.1 The current problematic computing ……………………………9 3.2 Applications ………………………………………………….……….9 3.3 Will NGSCB be the solution? …………………………….………9 4.References …………………………………………………………....10 Joseph Yu and Jeffrey Khuu Computer Network Management Page 2 of 10 Trusted Computing (TC) and Next Generation Secured Computing Base (NGSCB) 1. Introduction Overview 1.1 The Trusted Computing ² Trusted Computing (TC) The term Trusted Computing (TC) means the computer security integrated with hardware and software security components. As Ross Anderson suggested, the original motivation of TC was intended for digital rights management (DRM); that limits the abuse of file sharing over the network and making illegal copies without the authorization from the vendors, perhaps, restrict user's computing actions. -
An Introduction to Computer Security: the NIST Handbook U.S
HATl INST. OF STAND & TECH R.I.C. NIST PUBLICATIONS AlllOB SEDS3fl NIST Special Publication 800-12 An Introduction to Computer Security: The NIST Handbook U.S. DEPARTMENT OF COMMERCE Technology Administration National Institute of Standards Barbara Guttman and Edward A. Roback and Technology COMPUTER SECURITY Contingency Assurance User 1) Issues Planniii^ I&A Personnel Trairang f Access Risk Audit Planning ) Crypto \ Controls O Managen»nt U ^ J Support/-"^ Program Kiysfcal ~^Tiireats Policy & v_ Management Security Operations i QC 100 Nisr .U57 NO. 800-12 1995 The National Institute of Standards and Technology was established in 1988 by Congress to "assist industry in the development of technology . needed to improve product quality, to modernize manufacturing processes, to ensure product reliability . and to facilitate rapid commercialization ... of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national standards of measurement, and provide the means and methods for comparing standards used in science, engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal Government. As an agency of the U.S. Commerce Department's Technology Administration, NIST conducts basic and applied research in the physical sciences and engineering, and develops measurement techniques, test methods, standards, and related services. The Institute does generic and precompetitive work on new and advanced technologies. NIST's research facilities are located at Gaithersburg, MD 20899, and at Boulder, CO 80303. -
Expanding Malware Defense by Securing Software Installations*
Expanding Malware Defense by Securing Software Installations? Weiqing Sun1, R. Sekar1, Zhenkai Liang2 and V.N. Venkatakrishnan3 1 Department of Computer Science, Stony Brook University 2 Department of Computer Science, Carnegie Mellon University 3 Department of Computer Science, University of Illinois, Chicago. Abstract. Software installation provides an attractive entry vector for malware: since installations are performed with administrator privileges, malware can easily get the en- hanced level of access needed to install backdoors, spyware, rootkits, or “bot” software, and to hide these installations from users. Previous research has been focused mainly on securing the execution phase of untrusted software, while largely ignoring the safety of installations. Even security-enhanced operating systems such as SELinux and Vista don't usually impose restrictions during software installs, expecting the system administrator to “know what she is doing.” This paper addresses this “gap in armor” by securing software installations. Our technique can support a diversity of package managers and software installers. It is based on a framework that simplifies the development and enforcement of policies that govern safety of installations. We present a simple policy that can be used to prevent untrusted software from modifying any of the files used by benign software packages, thus blocking the most common mechanism used by malware to ensure that it is run automatically after each system reboot. While the scope of our technique is limited to the installation phase, it can be easily combined with approaches for secure execution, e.g., by ensuring that all future runs of an untrusted package will take place within an administrator-specified sandbox. -
Topic 20: TCSEC and Common Criteria
Information Security CS 526 Topic 20: TCSEC and Common Criteria CS526 Topic 20: TCSEC and Common 1 Criteria Related Readings for This Lecture • Wikipedia – Trusted computing base – TCSEC – Common Criteria, – Evaluation Assurance Level CS526 Topic 20: TCSEC and Common 2 Criteria Terminology: Trusted Computing Base (TCB) • The set of all hardware, software and procedural components that enforce the security policy. – In order to break security, an attacker must subvert one or more of them. – The smaller the TCB, the more secure a system is. • What consists of the conceptual Trusted Computing Based in a Unix/Linux system? – hardware, kernel, system binaries, system configuration files, setuid root programs, etc. One approach to improve security is to reduce the size of TCB, i.e., reduce what one relies on for security. CS526 Topic 20: TCSEC and Common 3 Criteria Assurance • Assurance: “estimate of the likelihood that a system will not fail in some particular way” • Based on factors such as – Software architecture • E.g., kernelized design, – Development process – Who developed it – Technical assessment CS526 Topic 20: TCSEC and Common 4 Criteria Kernelized Design User space • Trusted Computing Base User – Hardware and software for process enforcing security rules • Reference monitor – Part of TCB – All system calls go through Reference reference monitor for security monitor checking TCB – Most OS not designed this way OS kernel Kernel space CS526 Topic 20: TCSEC and Common 5 Criteria Reference Monitor • Three required properties for reference