Information Exposure through Microarchitectural State after Transient Execution

Modern CPUs use techniques like speculative execution and microcode assists to boost performance. When these operations are canceled or encounter errors, the processor should fully clean up. However, if remnants of these transient computations persist in internal buffers (like load/store queues), they create a measurable change in the chip's hidden state. An attacker can then use timing or other side-channel attacks to infer protected data, such as secrets from other processes or virtual machines. Successful exploitation typically requires three conditions: first, vulnerable code must speculatively access sensitive information, leaving microarchitectural traces. Second, the attacker must be able to trigger the specific CPU exceptions or mis-speculations that create these traces. Finally, the attacker needs a method to observe the state change, often by analyzing cache timing or other hardware resource contention, to slowly reconstruct the leaked data.