The warning is a common one: choose a strong password. Don't use "password" as your password. Don't use "123456" as your password. Yet every year a report or two surfaces showing those and dozens like them are the passwords of choices for users across the globe, not to mention passwords that are easy to guess once you know something about the user. One would expect hackers to be a collective well-versed in the need to choose hard-to-guess passwords, but even hackers make mistakes.