Have there been any documented cases where an engineer (or whatever) on a physical device or product used in the general marketplace has included a backdoor that allows them to get special "benefits"? Examples inside.
Some made up examples: an engineer on an ATM includes a secret code in the OS that allows the engineer to withdraw $100 without a card. Or a Otis Elevator engineer that includes a code allowing her to have express service if she hits the buttons in a certain order. The engineer who can hit a code in a certain order and get a free Coke. You get the idea--a backdoor that allows the engineer
him or herself to get a tangible and direct benefit. I'm presuming in my hypotheticals that the engineer's employer doesn't know or condone the back door.
I'm not looking for purely software backdoors (i.e., a code allowing a programmer to log in to a server with a secret master password), or for backdoors that aren't direct tangible benefits to the engineer (like the brouhaha over Diebold voting machines overriding votes for one party or another--whether or not that was malicious, it's not the kind of direct benefit for the responsible parties). So phreaking
is not what I'm looking for, either.
Has this kind of real-world back door ever been documented as a real thing? Free Cokes, express elevators, funny money, free RedBox DVDs etc.?