L0phtCrack is a password auditing and recovery application (now called L0phtCrack 7) originally produced by Mudge from L0pht Heavy Industries. It is used to test password strength and sometimes to recover lost Microsoft Windows passwords, by using dictionary, brute-force, hybrid attacks, and rainbow tables. It was one of the crackers' tools of choice, although most use old versions because of its low price and high availability.