Diminisher: A Linux Kernel Based Countermeasure for TAA Vulnerability

Abstract

TSX Asynchronous Abort (TAA) vulnerability is a class of Side-Channel Attack (SCA) that allows an application to leak data from internal CPU buffers through asynchronous Transactional Synchronization Extension (TSX) aborts that are exploited by the recent Microarchitectural Data Sampling (MDS) attacks. Cross-core TAA attacks can be prevented through microcode updates where CPU buffers are flushed during Operating System (OS) context switching, but there is no solution to our knowledge that exists for hyper-threaded TAA attacks in which the attacker leaks data from sibling hardware threads through asynchronous abort. In this work, we have proposed Diminisher, a Linux kernel-based detection and mitigation solution for both hyper-threaded and cross-core TAA attacks. Diminisher can be logically divided into three phases, i.e., scheduling, detection, and mitigation. Diminisher is a lightweight tool to prevent TAA vulnerability. The novelty lies in the methodology that we propose enabling easy extensions to cover other hyper-threaded attacks for which no satisfactory solutions exist yet. Diminisher detects and mitigates the TAA attacks around 99% of the time at a low-performance overhead of 2.5%.