On Disabling Prefetcher to Amplify Cache Side Channels

Abstract

Side-channel attacks exploit the hardware implementation of processors to extract sensitive data. Attacks that target shared resources between the victim and the attacker are prominent. A shared cache (available in today’s multi-core systems) between the attacker and victim has been shown to create a covert channel capable of leaking the private key. An attacker can extract the key by tracking the victim’s memory access pattern through the shared cache. Prefetchers introduce noise in the attack by speculatively bringing data into the cache that the victim may not use. This paper presents a denial of service (DoS) attack on the prefetcher to prevent it from generating memory accesses that interfere with the side-channel attack. The proposed attack aims to significantly reduce the number of prefetches generated to enable faster key retrieval. Our results show that the private key can be extracted with only 21% additional time in the presence of a prefetcher when the proposed attack is run (compared to a system with no prefetcher).