I believe this is possible. Discussed in detail with a proof-of-concept exploit at the latest CCC: https://media.ccc.de/v/35c3-9597-modchips_of_the_state#t=901

I believe this is possible. Discussed in detail with a proof-of-concept exploit at the latest CCC: https://media.ccc.de/v/35c3-9597-modchips_of_the_state#t=901 https://media.ccc.de/v/35c3-9597-modchips_of_the_state#t=901 Edit: this is a slightly different attack, it replaces a resistor with a custom chip that alters the transmission on that line (carefully disconnects the line, turning some 1s into 0s). But it should be possible to fit something like that inside a PCB, when the layers are put together.