What type of attack involves unauthorized access through a program entering a long list of passwords?

The scenario described pertains to a brute force attack, which is characterized by an unauthorized user attempting to gain access to a system by systematically entering a long list of possible passwords until the correct one is found. This method relies on the fundamental principle of trial and error, where the attacker uses either automated software or manually inputs multiple password combinations in rapid succession.

Brute force attacks exploit the weaknesses of weak or commonly used passwords, emphasizing the importance of strong password policies and account lockout mechanisms to mitigate such risks. By using this technique, an attacker can potentially gain unauthorized access to user accounts, systems, or networks, depending solely on the strength of the password being tested.

The other options represent different types of attacks or malicious activities. For instance, a denial of service attack disrupts the availability of a service, a botnet refers to a network of compromised machines used to automate tasks, and a buffer overflow is a vulnerability that can allow for arbitrary code execution. Each of these operates on different principles and methods, which is why they do not pertain to the login brute force scenario presented in the question.