sucrack is a multithreaded Linux/UNIX tool for brute-force cracking local user accounts via su.

This tool comes in handy when you've gained access to a low-privilege user account but are allowed to su to other users. Many su implementations require a pseudo terminal to be attached in order to take the password from the user. This can't be easily achieved with a simple shell script. This tool, written in C, is highly efficient and can attempt multiple logins at the same time.

Please be advised that using this tool will take a lot of the CPU performance and fill up the logs quite quickly. sucrack is so far known to be running on FreeBSD, NetBSD, Linux.

Check out the Usage and Examples page for more information.