CD Key stealing

I want to know how people steal cd keys, I know they make some sort of program then put it in a youtube video description, but how do they make the program and take it and replace it with a banned key?

There are a couple of different CD key stealing programs out there. Some are for sale, some are private. They are usually written in C++ and their function is to go into your registry and steal your key. Some smart CD key stealers will have their program not only take your CD key, but change it at the same time to either a banned one or an invalid one. Take GH0ST T3AM's key stealer for example. He advertises it on YouTube as a free bypass and leaves the download link to his key stealer in the description. Some poor kid who doesn't know what he is doing downloads and runs the program. The program then steals his key, changes it to another one and sends the victims key to GH0ST T3AM's e-mail.