Embedded systems are increasingly pervasive, interdependent and in many cases critical to our every day life and safety Tiny devices that cannot afford sophisticated hardware security mechanisms are embedded in complex control infrastructures, medical support systems and entertainment products [51] As such devices are increasingly subject to attacks, new hardware protection mechanisms are needed to provide the required resilience and dependency at low costIn this work, we present the TrustLite security architecture for flexible, hardware-enforced isolation of software modules We describe mechanisms for secure exception handling and communication between protected modules, enabling seamless interoperability with untrusted operating systems and tasks TrustLite scales from providing a simple protected firmware runtime to advanced functionality such as attestation and trusted execution of userspace tasks Our FPGA prototype shows that these capabilities are achievable even on low-cost embedded systems

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TrustLite: a security architecture for tiny embedded devices

Phishing, or web spoofing, is a growing problem: the Anti-Phishing Working Group (APWG) received almost 14,000 unique phishing reports in August 2005, a 56% jump over the number of reports in December 2004 [3]. For financial institutions, phishing is a particularly insidious problem, since trust forms the foundation for customer relationships, and phishing attacks undermine confidence in an institution. Phishing attacks succeed by exploiting a user's inability to distinguish legitimate sites from spoofed sites. Most prior research focuses on assisting the user in making this distinction; however, users must make the right security decision every time. Unfortunately, humans are ill-suited for performing the security checks necessary for secure site identification, and a single mistake may result in a total compromise of the user's online account. Fundamentally, users should be authenticated using information that they cannot readily reveal to malicious parties. Placing less reliance on the user during the authentication process will enhance security and eliminate many forms of fraud. We propose using a trusted device to perform mutual authentication that eliminates reliance on perfect user behavior, thwarts Man-in-the-Middle attacks after setup, and protects a user's account even in the presence of keyloggers and most forms of spyware. We demonstrate the practicality of our system with a prototype implementation.

Phoolproof Phishing Prevention

A trusted path is a protected channel that assures the secrecy and authenticity of data transfers between a user's input/output (I/O) device and a program trusted by that user We argue that, despite its incontestable necessity, current commodity systems do not support trusted path with any significant assurance This paper presents a hyper visor-based design that enables a trusted path to bypass an untrusted operating-system, applications, and I/O devices, with a minimal Trusted Computing Base (TCB) We also suggest concrete I/O architectural changes that will simplify future trusted-path system design Our system enables users to verify the states and configurations of one or more trusted-paths using a simple, secret less, hand-held device We implement a simple user-oriented trusted path as a case study

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Building Verifiable Trusted Path on Commodity x86 Computers

Application security traditionally strongly relies upon security of the underlying operating system. However, operating systems often fall victim to software attacks, compromising security of applications as well. To overcome this dependency, Intel SGX allows to protect application code against a subverted or malicious OS by running it in a hardware-protected enclave. However, SGX lacks support for generic trusted I/O paths to protect user input and output between enclaves and I/O devices. This work presents SGXIO, a generic trusted path architecture for SGX, allowing user applications to run securely on top of an untrusted OS, while at the same time supporting trusted paths to generic I/O devices. To achieve this, SGXIO combines the benefits of SGX's easy programming model with traditional hypervisor-based trusted path architectures. Moreover, SGXIO can tweak insecure debug enclaves to behave like secure production enclaves. SGXIO surpasses traditional use cases in cloud computing and digital rights management and makes SGX technology usable for protecting user-centric, local applications against kernel-level keyloggers and likewise. It is compatible to unmodified operating systems and works on a modern commodity notebook out of the box. Hence, SGXIO is particularly promising for the broad x86 community to which SGX is readily available.

SGXIO: Generic Trusted I/O Path for Intel SGX

To be trustworthy, security-sensitive applications must be formally verified and hence small and simple, i.e., wimpy. Thus, they cannot include a variety of basic services available only in large and untrustworthy commodity systems, i.e., in giants. Hence, wimps must securely compose with giants to survive on commodity systems, i.e., rely on giants' services but only after efficiently verifying their results. This paper presents a security architecture based on a wimpy kernel that provides on-demand isolated I/O channels for wimp applications, without bloating the underlying trusted computing base. The size and complexity of the wimpy kernel are minimized by safely outsourcing I/O subsystem functions to an untrusted commodity operating system and exporting driver and I/O subsystem code to wimp applications. Using the USB subsystem as a case study, this paper illustrates the dramatic reduction of wimpy-kernel size and complexity, e.g., over 99% of the USB code base is removed. Performance measurements indicate that the wimpy-kernel architecture exhibits the desired execution efficiency.

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Dancing with Giants: Wimpy Kernels for On-Demand Isolated I/O

Commodity computer systems today do not include a full trusted path capability. Consequently, malware can control the user's input and output in order to reveal sensitive information to malicious parties or to generate manipulated transaction requests to service providers. Recent hardware offers compelling features for remote attestation and isolated code execution, however, these mechanisms are not widely used in deployed systems to date. We show how to leverage these mechanisms to establish a “one-way” trusted path allowing service providers to gain assurance that users' transactions were indeed submitted by a human operating the computer, instead of by malware such as transaction generators. We design, implement, and evaluate our solution, and argue that it is practical and offers immediate value in e-commerce, as a replacement for captchas, and in other Internet scenarios.

Ahmad-Reza Sadeghiz

Papers

Uni-directional trusted path: Transaction confirmation on just one device