What is the primary purpose of a botnet controlled by a bot-herder?

The primary purpose of a botnet controlled by a bot-herder is to conduct coordinated attacks or malicious activities. A botnet comprises a collection of compromised devices, often referred to as "bots," which are manipulated without the owners' consent. The bot-herder manages these devices to perform various malicious tasks, such as launching Distributed Denial of Service (DDoS) attacks, sending spam emails, stealing personal information, or spreading malware.

Using a botnet for such coordinated attacks allows the bot-herder to harness the combined computing power of numerous infected devices, making their attacks more potent and difficult to mitigate. This strategic capacity makes botnets attractive to cybercriminals, enabling them to pursue illegal activities on a large scale while remaining largely undetected.

Other options do not accurately reflect the main intent behind a botnet. Providing free internet access is not a goal of botnets; instead, they exploit victim systems. Encrypting user data typically refers to ransomware attacks, not the general function of botnets. Lastly, while some botnets might gather statistical data, such activities are secondary to their primary function of carrying out malicious operations. Thus, the focus on coordinated attacks highlights the true essence of a botnet's purpose.