[rrix2]

The assembler still has to put a special SKU 5k resistor (with our BMC modifying framework burnt in to it) on the modified PCB without anyone noticing though. I don't follow your conclusion that only the PCBs would have to be swapped.

[mrb]

The attackers supposedly installed the tiny rogue chip, sandwiched between the layers of the PCB (which is unusual and the main innovation of this whole attack), before the PCBs reached the assembler. The assembler start soldering components without knowing one is already hidden in there...