Earlier this week, a team of security researchers from the Georgia Institute of Technology and Ruhr University Bochum presented a pair of papers on two side-channel speculative execution attacks targeted at Apple silicon, dubbed SLAP and FLOP [h/t Bleeping Computer]. A dedicated web page for the attacks, showing some examples, documentation, and links to the original two papers, is also available at the aptly-named URL Predictors.Fail.
So, what are these attacks? To understand either, you first need a working understanding of what speculative execution attacks are. In March of last year, I covered a speculative execution attack called GhostRace, and back in 2016, the one-two punch of the Meltdown and Spectre attacks helped introduce the concept into the wider public consciousness. "Speculative execution" isn't a bad thing in and of itself— you can think of it as a performance optimization that lets a CPU "speculate" what it needs to execute next— but unless it's tightly controlled, it is prone to security exploits that are near-impossible to fix without performance degradation.
