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.
Isolating an application from such an untrusted OS is essential for any trusted path. There exist various techniques for isolated execution, which range from pure hypervisor designs @cite_13 @cite_30 @cite_26 @cite_35 @cite_37 @cite_25 over hardware-software co-designs @cite_54 @cite_57 @cite_40 to pure hardware extensions @cite_31 @cite_12 @cite_60 @cite_29 @cite_8 @cite_16 @cite_23 . SGXIO uses Intel SGX @cite_29 , which, from a functional perspective, cumulates previous work in software isolation, attestation and transparent memory encryption. Others isolate sensitive code by keeping it entirely in the CPU cache @cite_47 or by migrating it to system management RAM on x86 @cite_3 . Often, dedicated security co-processors are used @cite_1 .
@cite_30 @cite_35 @cite_54 @cite_29 @cite_3 @cite_31 @cite_60 @cite_8 @cite_23 @cite_37 @cite_26 @cite_57 @cite_40 @cite_16 @cite_25 @cite_12 @cite_1 @cite_47 @cite_13
2583196029 2607063282 2011491452 2889224812
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. Shielded execution based on Intel SGX provides strong security guarantees for legacy applications running on untrusted platforms. However, memory safety attacks such as Heartbleed can render the confidentiality and integrity properties of shielded execution completely ineffective. To prevent these attacks, the state-of-the-art memory-safety approaches can be used in the context of shielded execution. In this work, we first showcase that two prominent software- and hardware-based defenses, AddressSanitizer and Intel MPX respectively, are impractical for shielded execution due to high performance and memory overheads. This motivated our design of SGXBounds---an efficient memory-safety approach for shielded execution exploiting the architectural features of Intel SGX. Our design is based on a simple combination of tagged pointers and compact memory layout. We implemented SGXBounds based on the LLVM compiler framework targeting unmodified multithreaded applications. Our evaluation using Phoenix, PARSEC, and RIPE benchmark suites shows that SGXBounds has performance and memory overheads of 17 and 0.1 respectively, while providing security guarantees similar to AddressSanitizer and Intel MPX. We have obtained similar results with SPEC CPU2006 and four real-world case studies: SQLite, Memcached, Apache, and Nginx. We consider the problem of how to provide an execution environment where the application's secrets are safe even in the presence of malicious system software layers. We propose Iso-X --- a flexible, fine-grained hardware-supported framework that provides isolation for security-critical pieces of an application such that they can execute securely even in the presence of untrusted system software. Isolation in Iso-X is achieved by creating and dynamically managing compartments to host critical fragments of code and associated data. Iso-X provides fine-grained isolation at the memory-page level, flexible allocation of memory, and a low-complexity, hardware-only trusted computing base. Iso-X requires minimal additional hardware, a small number of new ISA instructions to manage compartments, and minimal changes to the operating system which need not be in the trusted computing base. The run-time performance overhead of Iso-X is negligible and even the overhead of creating and destroying compartments is modest. Iso-X offers higher memory flexibility than the recently proposed SGX design from Intel, allowing both fluid partitioning of the vailable memory space and dynamic growth of compartments. An FPGA implementation of Iso-X runtime mechanisms shows a negligible impact on the processor cycle time. Intel Software Guard Extensions (SGX) isolate security-critical code inside a protected memory area called enclave. Previous research on SGX has demonstrated that memory corruption vulnerabilities within enclave code can be exploited to extract secret keys and bypass remote attestation. However, these attacks require kernel privileges, and rely on frequently probing enclave code which results in many enclave crashes. Further, they assume a constant, not randomized memory layout. In this paper, we present novel exploitation techniques against SGX that do not require any enclave crashes and work in the presence of existing SGX randomization approaches such as SGX-Shield. A key contribution of our attacks is that they work under weak adversarial assumptions, e.g., not requiring kernel privileges. In fact, they can be applied to any enclave that is developed with the standard Intel SGX SDK on either Linux or Windows.