Solution:

• The term that refers to a group of computers controlled without their owner’s knowledge and used to send spam or make denial of service attacks is “Botnet”.
• A botnet is a network of compromised computers (often called “bots” or “zombies”) that are under the control of a malicious actor.
• These computers are typically infected with malware, allowing the attacker to commandeer them remotely for various purposes, including sending spam, launching DDoS (Distributed Denial of Service) attacks, or engaging in other malicious activities without the knowledge or consent of the computer owners.