Some guy creates a worm that just changes your wallpaper to get your attention... you get the worm, and after a WTF moment, you google search and find out that you can easily remove the "worm", and that the reason why you got the it is because you were a stupid dickhead and didn't change a default password. You change the password, and thus avoid getting something legitimately harmful.
Yeah, that guy's a real asshole. Nobody should hire him /sarcasm.