Which of the following types of attacks is often performed by looking surreptitiously at the keyboard or monitor of an employee's computer?

A Man-in-the-middle attack involves an attacker intercepting communication between two parties without their knowledge, altering or eavesdropping on the exchanged data.

A Denial-of-Service (DoS) attack aims to make a machine or network resource unavailable to its intended users by overwhelming it with traffic or exploiting vulnerabilities.

A buffer-overflow attack occurs when a program attempts to write data to a buffer that is larger than the buffer's allocated capacity, potentially overwriting adjacent memory and leading to arbitrary code execution.

Shoulder surfing is a social engineering attack where an attacker directly observes a person's private information, such as passwords, PINs, or data displayed on a screen, by looking over their shoulder.