Apple Silicon Vulnerabilities Highlighted by FLOP & SLAP Side-channel Attacks
An academic collaboration—between research departments at Georgia Institute of Technology and Ruhr University Bochum—has produced two white paper studies that disclose details regarding the vulnerable nature of certain generations of Apple Silicon. The documents were made available online earlier in the week; readily accessible through their Predictors.Fail webpage. The "SLAP" attack paper's moniker is derived/abbreviated from its long-form title: "Data Speculation Attacks via Load Address Prediction on Apple" Silicon. A similarly uncatchy acronymization has been generated by the second paper's full title: "Breaking the Apple M3 CPU via False Load Output Predictions"—aka "FLOP" attack. The North American and German security research teams have partnered up in the past—their "iLeakage" speculative execution side-channel attack was documented back in October 2023.
Spectre and Meltdown are the original, and likely most famous/notorious examples of speculative execution CPU vulnerability—owners of particular processor architectures were affected at the start of 2018. The Predictors.Fail bulletin proposes that the latest side-channel attacks affect Apple hardware of 2021 vintage and beyond. The teams introduced SLAP as: "a new speculative execution attack that arises from optimizing data dependencies, as opposed to control flow dependencies." They believe that Apple models: "starting with the M2 and A15 are equipped with a Load Address Predictor (LAP), which improves performance by guessing the next memory address the CPU will retrieve data from based on prior memory access patterns. However, if the LAP guesses wrong, it causes the CPU to perform arbitrary computations on out-of-bounds data, which should never have been accessed to begin with, under speculative execution. Building on this observation, we demonstrate the real-world security risks of the LAP via an end-to-end attack on the Safari web browser, where an unprivileged remote adversary can recover email content and browsing behavior."
Spectre and Meltdown are the original, and likely most famous/notorious examples of speculative execution CPU vulnerability—owners of particular processor architectures were affected at the start of 2018. The Predictors.Fail bulletin proposes that the latest side-channel attacks affect Apple hardware of 2021 vintage and beyond. The teams introduced SLAP as: "a new speculative execution attack that arises from optimizing data dependencies, as opposed to control flow dependencies." They believe that Apple models: "starting with the M2 and A15 are equipped with a Load Address Predictor (LAP), which improves performance by guessing the next memory address the CPU will retrieve data from based on prior memory access patterns. However, if the LAP guesses wrong, it causes the CPU to perform arbitrary computations on out-of-bounds data, which should never have been accessed to begin with, under speculative execution. Building on this observation, we demonstrate the real-world security risks of the LAP via an end-to-end attack on the Safari web browser, where an unprivileged remote adversary can recover email content and browsing behavior."