What type of attack occurs when an intruder guesses a password through rapid attempts, locking out legitimate users?

A brute force attack is a method used by intruders to gain unauthorized access to an account or system by systematically trying every possible password until the correct one is discovered. This approach can involve rapidly generating and testing multiple password combinations, often using automated tools to speed up the process. When an intruder executes a brute force attack, they may cause legitimate users to be locked out of their accounts due to security measures such as account lockout policies, which are designed to protect against unauthorized access. These policies typically limit the number of login attempts allowed in a specified timeframe, and excessive failed attempts can trigger a temporary suspension for legitimate users, leading to frustration and disruption of service.

The other options refer to different types of attacks: social engineering involves manipulating individuals into divulging confidential information, a DDoS (Distributed Denial of Service) attack aims to overwhelm a service with traffic to make it unavailable, and a man-in-the-middle attack occurs when an intruder intercepts the communication between two parties without their knowledge. Each of these methods targets different vulnerabilities and utilizes distinct strategies compared to the direct password guessing approach of a brute force attack.