Hardware backdoors in some x86 CPUs

The top story on Hacker News unveils the deeply unsettling discovery of hardware backdoors within certain x86 CPUs. This research, spearheaded by Christopher Domas, reveals a non-x86 core embedded alongside the main processor that can bypass critical security checks, potentially granting user-level code (ring 3) unauthorized access to kernel data (ring 0). While initially believed to require kernel access to activate, some systems have been found with this backdoor enabled by default, making them vulnerable to unprivileged code execution. This vulnerability, distinct from other known coprocessors like the Management Engine, offers a more profound level of system compromise, negating decades of progress in kernel security mechanisms. This finding, though related to older VIA C3 processors, serves as a critical case study illustrating how hardware backdoors can emerge in increasingly complex CPU architectures, posing a more severe and harder-to-detect threat than typical software supply chain issues.