Which type of malware is used to control computers in a zombie network?

The correct choice, which is botnet, refers to a collection of compromised devices that are controlled by a central command, often without the knowledge of the device owners. A botnet is typically created when malware infects devices, turning them into "zombies." This allows an attacker to control these devices remotely and carry out various malicious activities, such as launching Distributed Denial of Service (DDoS) attacks, sending spam, or stealing information.

Understanding the function of a botnet highlights its significance in the context of cybersecurity threats. Devices in a botnet can be manipulated to coordinate actions, making them a powerful tool for cybercriminals to exert control over multiple machines.

The other types of malware mentioned do not serve the same purpose. Trojan horses are designed to appear as legitimate software to deceive users into installing them, but they do not inherently create a network of controlled devices. Worms are self-replicating malware that spread without user intervention but do not necessarily control other devices like a botnet does. Spyware is meant to gather information from a user's device without their consent, focusing on data theft rather than the orchestration of a network of compromised machines.