In high school, I wrote a program that drew a realistic picture of our login screen, with two real inputs for username and password. No matter what you typed

In high school, I wrote a program that drew a realistic picture of our login screen, with two real inputs for username and password. No matter what you typed in those boxes, my program would save it to a text file in my home directory, and then log me out, which would instantly display the real login prompt. I didn't have any real reason to steal everyone's credentials including the teacher's, but it was fun. And I would have gotten away with it, if I wasn't storing the output in a file called stolen_passwords.txt! I got busted, and the teacher said I could either take 23 saturday detentions, or help him fix the login screen so that my attack wouldn't work anymore. I made an honest effort at the latter, and he let me off.