Prevention
Not a real threat nowadays, due to:
complexity of the designs
size of state-of-the-art FPGAs.
Common I/O pins which makes it difficult to connect to the right pin.
An attacker has to connect to device’s pin of a known function like,
Microprocessor interrupt input,
And also,
Figure out whether to:
Drive a pin with a voltage,
Sense its output state, or both isn’t a straightforward exercise.