That is possible but unlikely. Firstly you'd have to do this at the PCB fab phase as this can't be retrospectively applied, so you'd have to have infiltrated tw

That is possible but unlikely. Firstly you'd have to do this at the PCB fab phase as this can't be retrospectively applied, so you'd have to have infiltrated two times as many companies and add complex manufacturing exceptions to their workflow. Secondly you'd have to get it through AXI process which is used on these larger boards (Automated X-ray Inspection) which is used by the larger companies for manufacturing AND design validation. So you'd have to infiltrate another company. Also stuff like this tends to show up on boundary scans. It's not that easy to cock around with signal integrity on these sorts of boards and get away with it. I find the whole thing infeasible from a cost and logic perspective. The SMbus firmware and Aspeed sub-vendor are so much easier to hit and don't leave any corpses around to find after the fact.