Which of the following is an example of a brute force attack?

A brute force attack refers specifically to a method where an attacker systematically attempts all possible combinations of passwords or encryption keys until the correct one is found. This approach relies on trial and error, making it a straightforward but time-consuming and resource-intensive method of gaining unauthorized access.

The correct choice exemplifies this concept by describing the act of attempting multiple password combinations until access is granted. This method does not require any sophisticated techniques or insider knowledge, as it simply leverages the sheer volume of possible combinations.

The other options involve different methods of attack: using scripts to break encryption focuses on exploiting the encryption method rather than guessing, impersonating a user is a form of social engineering or identity theft, and exploiting software vulnerabilities involves taking advantage of flaws in software rather than attempting to guess passcodes. Each of these methods represents different strategies for gaining unauthorized access, distinct from the brute force approach.