A Password Cracker is software that is used to discover secret passwords on a computer or network. While Password Crackers have legitimate uses, they may ... used by an attacker to gain unauthorized access to a computer or network without the user's or network administrator's knowledge and consent. A Password Stealer is software that surreptitiously captures passwords, typically used by an attacker to gain unauthorized access to a computer or network or to obtain login credentials for financial accounts and institutions. Password Crackers and Stealers are often designed to be executed and used in stealth mode, undetected by computer users and network administrators.