What is a Botnet?
A botnet is a network of computers, internet of things (IoT) devices, smartphones and other connected devices that are infected with malware and under the control of a cybercriminal. The hacker, who is known as a “bot-herder,” uses the compromised devices to carry out massive cyberattacks on a scale that far exceeds what he or she can accomplish alone.
Once the hacker infects a device with bot malware, the infected machine links back to a command and control (C&C) server that sends instructions to the bots. The C&C server assigns tasks to the bots, which can range from sending spam to conducting DDoS attacks. Bots can also monetize their activities by mining cryptocurrencies or stealing personal information such as usernames and passwords.
Attackers use a variety of methods to infect devices, including phishing emails, drive-by downloads and vulnerabilities in operating systems and applications. Many of these attacks leverage social engineering tactics such as luring users to click on malicious links. To protect yourself, always manually enter the address of a link rather than clicking on it, and install a robust internet security suite that includes antivirus software for all your connected devices.
After a botnet is established, the bot-herder may sell or rent it to other cybercriminals on the dark web or black market. These buyers can then use the botnet to launch coordinated attacks, such as DDoS, ad fraud and mass email spam. The infamous Srizbi botnet grew to encompass thousands, if not millions, of computers and IoT devices at its peak.