Developer reproduces CPU-based covert channel between Firecracker microVMs

A developer created cpu-chat, which reproduces the CPU-based covert communication demonstrated by OpenAI between two or more Firecracker microVMs, working on x86 and Apple M5 systems. Using three mechanisms (CPU contention, cache eviction timing, DRAM bandwidth) they overcame Firecracker's manufacturing recommendations, posing a security risk and detection challenge in multi-tenant environments.