A botnet is a network of computers or devices that are infected by malware and controlled by a malicious actor, known as the botmaster or bot-herder. The botmaster uses a command and control (C2) server or channel to send instructions to the bots and receive information from them. The C2 communication is essential for the botmaster to maintain control over the botnet and use it for various malicious purposes, such as launching distributed denial-of-service (DDoS) attacks, stealing data, sending spam, or mining cryptocurrency. Therefore, the key to “taking down” a botnet is to prevent the bots from communicating with the C2 server or channel. This can be done by disrupting, blocking, or hijacking the C2 communication, which can render the botnet ineffective, unstable, or inaccessible. For example, security researchers or law enforcement agencies can use techniques such as sinkholing, domain name system (DNS) poisoning, or domain seizure to redirect the bot traffic to a benign server or a dead end, cutting off the connection between the bots and the botmaster. Alternatively, they can use techniques such as reverse engineering, decryption, or impersonation to infiltrate the C2 server or channel and take over the botnet, either to disable it, monitor it, or use it for good purposes. References:

What is a Botnet? - Palo Alto Networks

Botnet Detection and Prevention Techniques | A Quick Guide - XenonStack

Botnet Mitigation: How to Prevent Botnet Attacks in 2024 - DataDome

What is a Botnet? Definition and Prevention | Varonis