CacheZoom: How SGX Amplifies The Power of Cache Attacks

In modern computing environments, hardware resources are commonly shared, and parallel computation is widely used. Parallel tasks can cause privacy and security problems if proper isolation is not enforced. Intel proposed SGX to create a trusted execution environment within the processor. SGX relies on the hardware, and claims runtime protection even if the OS and other software components are malicious. However, SGX disregards side-channel attacks. We introduce a powerful cache side-channel attack that provides system adversaries a high resolution channel. Our attack tool named CacheZoom is able to virtually track all memory accesses of SGX enclaves with high spatial and temporal precision. As proof of concept, we demonstrate AES key recovery attacks on commonly used implementations including those that were believed to be resistant in previous scenarios. Our results show that SGX cannot protect critical data sensitive computations, and efficient AES key recovery is possible in a practical environment. In contrast to previous works which require hundreds of measurements, this is the first cache side-channel attack on a real system that can recover AES keys with a minimal number of measurements. We can successfully recover AES keys from T-Table based implementations with as few as ten measurements.Comment: Accepted at Conference on Cryptographic Hardware and Embedded Systems (CHES '17

Drive-by Key-Extraction Cache Attacks from Portable Code

We show how malicious web content can extract cryptographic secret keys from the user\u27s computer. The attack uses portable scripting languages supported by modern browsers to induce contention for CPU cache resources, and thereby gleans information about the memory accesses of other programs running on the user\u27s computer. We show how this side-channel attack can be realized in both WebAssembly and PNaCl; how to attain very fine-grained measurements; and how to use these to extract ElGamal, ECDH and RSA decryption keys from various cryptographic libraries. The attack does not rely on bugs in the browser\u27s nominal sandboxing mechanisms, or on fooling users. It applies even to locked-down platforms with strong confinement mechanisms and browser-only functionality, such as Chromebook devices. Moreover, on browser-based platforms the attacked software too may be written in portable JavaScript; and we show that in this case even implementations of supposedly-secure constant-time algorithms, such as Curve25519\u27s, are vulnerable to our attack

An Evaluation of Bucketing in Systems with Non-deterministic Timing Behavior

Part 4: Software Security / AttacksInternational audienceTiming side-channel vulnerabilities constitute a serious threat against privacy and confidentiality of data. In this article, we study the effects of bucketing, a previously proposed mitigation technique against timing side channels. We present two implementations of bucketing that reside at the application and at the kernel level, respectively. We experimentally evaluate the effectiveness of these implementations in a setting with non-deterministic timing behavior, a practically relevant setting that has not been studied before. Our results show that the impact of non-deterministic timing behavior is substantial. The bucket boundaries cannot be established sharply and this reduces the effectiveness of bucketing. Nevertheless, bucketing still provides a significant reduction of side-channel capacity

An Evaluation of Bucketing in Systems with Non-Deterministic Timing Behavior

Part 4: Software Security / AttacksInternational audienceTiming side-channel vulnerabilities constitute a serious threat against privacy and confidentiality of data. In this article, we study the effects of bucketing, a previously proposed mitigation technique against timing side channels. We present two implementations of bucketing that reside at the application and at the kernel level, respectively. We experimentally evaluate the effectiveness of these implementations in a setting with non-deterministic timing behavior, a practically relevant setting that has not been studied before. Our results show that the impact of non-deterministic timing behavior is substantial. The bucket boundaries cannot be established sharply and this reduces the effectiveness of bucketing. Nevertheless, bucketing still provides a significant reduction of side-channel capacity