Which of the following best describes a botnet?

A botnet is accurately described as a group of compromised computers that are controlled by a hacker. These compromised machines, often referred to as "bots" or "zombies," are infected with malware that allows the hacker to control them remotely without the owners' knowledge. This control enables the perpetrator to launch coordinated attacks, send spam emails, steal data, or perform other malicious activities across the internet.

Understanding the characteristics of a botnet is crucial for cybersecurity, as it illustrates how attackers can harness the power of multiple devices to achieve their goals, making detection and mitigation more challenging. The collective strength of numerous compromised computers allows for larger scale attacks, often overwhelming targets with traffic or executing widespread tasks without raising immediate suspicion.

In contrast, the other options do not correctly define a botnet. A network of secure servers refers to a legitimate cluster of machines that provide services or resources in a secure manner, while antivirus software is designed to protect systems from malware rather than being part of a malicious framework. Finally, a single device used for hacking does not convey the collective nature that defines a botnet, which relies on a multitude of compromised systems working in unison.