Today a new variant of the ZombieLoad family of side-channel attacks has been made public. This new variant is called TSX Asynchronous Abort (TAA). TAA works on all recent Intel processors that support Intel TSX, including Intel's most recent Cascade Lake processors.
About a year ago, I (together with a small team of other security researchers) was waiting for Intel to disclose security vulnerabilities we had discovered in its microprocessor hardware. We expected a fair bit of excitement because the industry had been scrambling to get mitigations in place. However I was thoroughly gobsmacked by the kind of delayed fireworks unfolding in the media. More than a year has elapsed since then so it is only fair to ask what is left beyond the sound and smoke - and why it was not the beginning of the end of the familiar IT universe, as predicted by a couple of pessimists.
ZombieLoad is a novel category of side-channel attacks which we refer to as **data-sampling attack**. It demonstrates that faulting load instructions can transiently expose private values of one Hyperthread sibling to the other. This new exploit is the result of a collaboration between Michael Schwarz, Daniel Gruss and Moritz Lipp from Graz University of Technology, Thomas Prescher and Julian Stecklina from Cyberus Technology, Jo Van Bulck from KU Leuven, and Daniel Moghimi from Worcester Polytechnic Institute. In this article, we summarize the implications and shed light on the different attack scenarios across CPU privilege rings, OS processes, virtual machines, and SGX enclaves, and give advice over possible ways to mitigate such attacks.
After Meltdown and Spectre, more vulnerabilities in out-of-order CPUs have been uncovered that use similar side channels. This article is about the L1 Terminal Fault vulnerability, a meltdown-style attack that is also effective against up-to-date system software incorporating KPTI-like patches.
After Meltdown and Spectre, which were publicly disclosed in January, the Spectre V3a and V4 vulnerabilities followed in May. According to the German IT news publisher Heise, the latter might be part of eight new vulnerabilities in total that are going to be disclosed in the course of the year.
After Meltdown and Spectre, more vulnerabilities in out-of-order CPUs have been uncovered that use similar attack vectors. This article is about the new variant 4 of the Spectre attack that works without misleading the branch predictor. Instead, it exploits an implementation detail of Intel's memory disambiguation technique inside the CPU's pipeline.