A brute force attack is an attempt to log into a secure system by making lots of attempts in the hopes of eventual success. It’s not a sophisticated type of attack, hence the name "brute force." For example, if you have a login process that requires a username and password, there is a limit as to the possible number of username/password combinations. That limit may be in the billions or trillions, but still, it’s a finite number. Using algorithms and automated processes, a brute force attack repeatedly tries combinations until they succeed.