![]() ![]() "They treat this class of attacks differently than the class of 'speculative execution / transient execution attacks' (like Spectre, Meltdown, etc.). "Intel classified our attack as a 'traditional side channel' (like TLBleed, Portsmash, etc.)," said Paccagnella. Intel, which alongside the National Science Foundation helped support this research, isn't overly concerned about CPU bus-based meddling. Likewise, the researchers haven't looked at how their technique would work on ARM CPUs, which rely on different interconnect technology. It's unknown whether more recent Intel server chips with mesh interconnects are also susceptible. The attacks were tested on Intel Coffee Lake and Skylake CPUs, client-class CPUs, and should work on server CPUs like Xeon Broadwell. Foreshadow returns to the foreground: Secrets-spilling speculative-execution Intel flaw lives on, say boffins.Meltdown The Sequel strikes Intel chips – and full mitigation against data-meddling LVI flaw will slash performance.Thought you'd addressed those data-leaking Spectre holes on Linux? Guess again.Google looks at bypass in Chromium's ASLR security defense, throws hands up, won't patch garbage issue.It also assumes the system is set up to clear the target's cache footprint to prevent cache-based preemptive scheduling attacks. The cryptographic attack assumes that simultaneous multithreading (SMT) has been disabled, that the last level cache (LLC) has been partitioned to defend against multicore cache-based attacks, and memory sharing across security domains has been disabled. He said a cloud-based scenario, where the adversary is an admin or co-tenant of a shared system, may also be possible but he and his colleagues prefer not to make that claim because the demonstration attacks were run in a non-virtualized environment and haven't been tested in other circumstances. Paccagnella said the two attacks demonstrated involve a local attacker running unprivileged code on the victim's machine – such as malware hidden in a software library or application that snoops on other programs or users. Such observation is difficult because there's a lot of noise that needs to be identified and filtered out, and the meaningful events, such as private cache misses (when a system seeks data in a cache that isn't there), aren't all that common.īasically, these repeated memory loads can cause delays that reveal secrets to the observer. Second, their attack relies on contention, which in this instance involves monitoring latency when different processes access memory at the same time. So significant reverse engineering was required. The challenge faced by the researchers was twofold: first, Intel hasn't provided much detail about how its CPU ring bus works. ![]() They also showed they could monitor keystroke timing, which prior research has shown can be used to reconstruct typed passwords. In a paper to be presented at USENIX Security 2021 in August – "Lord of the Ring(s): Side Channel Attacks on the CPU On-Chip Ring Interconnect Are Practical" – Paccagnella, Luo, and Fletcher recount how they managed to figure out the workings of Intel's ring interconnect, or bus, that passes information between CPU cores.Īrmed with that understanding, they found they could leak cryptographic key bits from RSA and EdDSA implementations, which are already known to be vulnerable to side-channel attacks. ![]()
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