PhantomTac: A 0.5 mm magnetic label hidden under a barcode deceives the touch of robotic hands

Without ever touching the robot, an attacker can crush or release an object by sticking on a thin magnet label. Success rate: over 95%.

Magnetic touch sensors are popular in robotics: they finely measure forces in all three dimensions and are not hindered when the view is obscured. A team of researchers has discovered a physical flaw, called PhantomTac. By modifying the magnetic field perceived by the sensor, an attacker can make it believe in a force that does not exist.

Setting down and leaving

The attack fits in a magnetic tag about 0.5 mm thick, without a battery, stuck to the surface of an object and easy to hide under a barcode. Once landed, the attacker does not have to do anything. When a robotic hand grasps the object, a false normal force causes it to squeeze too hard and crush it, while a false shear force releases the grip until it drops. Unlike sabotaging the robot, no access to the machine is necessary.

After studying the operation of commercially available sensors in reverse, the authors tested their label on real robots and articulated arms. It bypasses existing interference protection and hijacks the input control loop in more than 95% of cases, as long as the grip point does not deviate by more than 8 mm. To prevent this, they propose to check the coherence between several directions of the robot.