source: https://www.securityfocus.com/bid/3186/info

A user who has set an Open Firmware password on their Apple system believes it to be safe when powered down. There is a tool that any user with access to the Finder can run in order to reveal the Open Firmware password without any decryption.

https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/21070.sit