Unpatchable vulnerability in Apple chip leaks secret encryption keys

Researchers have identified a critical vulnerability in Apple’s M-series chips that allows for the extraction of cryptographic keys during certain operations. This flaw is due to a side channel in the chips’ data memory-dependent prefetcher (DMP), which is designed to improve performance by predicting future data needs. However, the DMP can mistakenly treat cryptographic key material as a pointer, leading to unauthorized data access through a cache side channel. This vulnerability cannot be fixed with a direct patch as it is rooted in the chip’s microarchitecture. Instead, mitigation requires adjustments to cryptographic software, which could impact the performance of M-series chips, especially the M1 and M2.

The discovery by an academic team reveals that attackers can manipulate data to appear as pointers, which the DMP then prefetches, inadvertently leaking the data. This method can be used to reveal secret keys over time, circumventing the constant-time programming defenses typically used to prevent such side-channel attacks. The implications of this research are significant for the security of cryptographic operations on devices with M-series chips, necessitating a reevaluation of current cryptographic practices and defenses.
Read more at Ars Technica…