CPU frequency scaling is widely employed to dynamically adjust the speed and voltage of CPU cores in real time, aiming to achieve both high performance and power efficiency. Prior work indicates that variations in CPU frequency can leak information about the workload being processed. We find that the performance of I/O requests, such as file I/Os with a fast storage device, is affected by runtime changes in CPU frequency and, in turn, reflects the behavior of ongoing work- load. Accordingly, we develop IOLeak, a new side-channel built on CPU frequency scaling without directly accessing CPU frequency. We first construct an IOLeak covert channel by detecting I/O latency online for secretive communication, both with and without noise. Next, we leverage IOLeak to launch stealthy attacks, such as extracting cryptographic keys and fingerprinting websites and confirm that IOLeak manages to leak information through file I/Os.
We have made a webpage to present IOLeak. AMD has issued a relevant post. Should you have any question, please drop an email to cd_wang "the-at-sign" outlook.com.