Shadow Attacks on MEDA Biochips

The Micro-electrode-dot-array (MEDA) is a next-generation digital microfluidic biochip (DMFB) platform that supports fine-grained control and real-time sensing of droplet movements. These capabilities permit continuous monitoring and checkpoint-based validation of assay execution on MEDA. This paper presents a class of “shadow attacks” that abuse the timing slack in the assay execution. State-of-the-art checkpoint-based validation techniques cannot expose the shadow operations. We develop a defense that introduces extra checkpoints in the assay execution at time instances when the assay is prone to shadow attacks. Experiments confirm the effectiveness and practicality of the defense.