Apple-designed chips powering Macs, iPhones, and iPads contain two newly discovered vulnerabilities that leak credit card information, locations, and other sensitive data from the Chrome and Safari browsers as they visit sites such as iCloud Calendar, Google Maps, and Proton Mail.
The vulnerabilities, affecting the CPUs in later generations of Apple A- and M-series chip sets, open them to side channel attacks, a class of exploit that infers secrets by measuring manifestations such as timing, sound, and power consumption. Both side channels are the result of the chips’ use of speculative execution, a performance optimization that improves speed by predicting the control flow the CPUs should take and following that path, rather than the instruction order in the program.
A new direction
The Apple silicon affected takes speculative execution in new directions. Besides predicting control flow CPUs should take, it also predicts the data flow, such as which memory address to load from and what value will be returned from memory.
