Port contention goes portable: Port contention side channels in web browsers

Thomas Rokicki, Clémentine Maurice, Marina Botvinnik, Yossi Oren

Proceedings of the 2022 ACM on Asia Conference on Computer and …, 2022

Microarchitectural side-channel attacks can derive secrets from the execution of vulnerable programs. Their implementation in web browsers represents a considerable extension of their attack surface, as a user simply browsing a malicious website, or even a malicious third-party advertisement in a benign cross-origin isolated website, can be a victim.In this paper, we present the first port contention side channel running entirely in a web browser, despite a highly challenging environment. Our attack can be used to build a cross-browser covert channel with a bit rate of 200bps, one order of magnitude above the state of the art, and has a spatial resolution of 1024 native instructions in a side-channel attack, a performance on-par with Prime+Probe attacks. We provide a framework to evaluate the port contention caused by WebAssembly instructions on Intel processors, allowing to increase the portability of port …