Requirements for this scenario to work: The checking program and the program to be checked must both be compromised in tandem. This is covered in RoTT.

This has already happened in various areas. For one area, look at gambling (two decades ago). Ron Harris worked at the Nevada Gaming Control board as a tester of new systems and configued the field verification of those systems. Eventually he turned that into video gaming devices that would hit a jackpot after a certain button sequence was pressed.