sucrack binary package in Ubuntu Focal amd64

 sucrack is a multithreaded Linux/UNIX tool for cracking local
 user accounts via wordlist bruteforcing 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.

Source package