What is a Botnet?
A botnet is an army of malware-infected devices commanded by cybercriminals for malicious purposes. Bots can be used to carry out a variety of attacks, from flooding websites with traffic (distributed denial-of-service or DDoS) to harvesting passwords and other sensitive information for sale on the dark web.
Botnets start with malware that gets spread via phishing emails, sketchy apps, compromised websites, or software vulnerabilities. Once a device is infected, it phones home to a central command and control (C&C) server, where the bot herders are in control. The C&C servers then send commands to the bots on their network. The bots are programmed to automatically search for and infect new devices, growing the botnet like wildfire. Some bots are even designed to encrypt communications, obfuscate their activity, and try to re-infect devices after being removed.
The bots then execute the C&C commands, from launching DDoS attacks to stealing data or spamming users with fake emails. In addition, a botnet can be used to spy on the activities of users and collect keystrokes and screenshots for further exploits.
To prevent a botnet, the best protection is to keep all devices and applications up to date with patches, including IoT devices that often have less robust security. It is also important to limit the type of third-party code that can run on a device, and monitor ingress and egress traffic to detect and block suspicious activity. Finally, implementing a strong cybersecurity solution with a strong intrusion detection and prevention system (IDS/IPS), advanced endpoint protection, and secure passwords is critical.