For some reason you lost your master password to Firefox?  Do not worry as there’s a new tool called Firemaster that will recover your Firefox master password through brute-force hacks.  Really, though, you can also simply erase all your personal preferences by “uninstalling” your Firefox and re-installing it.

Firemaster really is for those who need to hack another’s computer…

Once you have lost master password, there is no way to recover it as it is not stored at all. Whenever user enters the master password, Firefox uses it to decrypt the encrypted data associated with the known string. If the decrypted data matches this known string then the entered password is correct. FireMaster uses the similar technique to check for the master password, but in more optimized way. The entire operation goes like this.

* FireMaster generates passwords on the fly through various methods.
* Then it computes the hash of the password using known algorithm.
* Next this password hash is used to decrypt the encrypted data for known plain text (i.e. “password-check”).
* Now if the decrypted string matches with the known plain text (i.e. “password-check”) then the generated password is the master password.

Firefox stores the details about encrypted string, salt, algorithm and version information in key database file key3.db in the user’s profile directory. You can just copy this key3.db file to different directory and specify the corresponding path to FireMaster. You can also copy this key3.db to any other high end machine for faster recovery operation.

via lifehacker