Definition
A botnet is a network of compromised computers, often called bots or zombies, controlled remotely by an attacker. These devices are infected with malware that allows the attacker to command them without the owner's knowledge or consent. The attacker, known as a botmaster, uses a command and control infrastructure to issue instructions to the botnet for malicious purposes. Botnets are frequently employed to launch distributed denial of service attacks, send spam emails, or steal sensitive information. While a botnet is a collection of infected machines, a single infected machine is simply a bot. Understanding botnets is crucial for cybersecurity professionals to defend against large scale attacks and is a common topic on exams like Security+, CySA+, and CISSP.