What is a Botnet?
A botnet is a network of computer devices (zombie computers) that are infected by malware and controlled remotely. The infected computers are used to conduct various cyber attacks, including denial of service (DDoS) attacks and data theft. Bots are commonly controlled by a person or organization known as the bot herder, who may use the botnet to perform illegal activities, such as ransomware, cyber espionage, and financial fraud.
Bot-herders control botnets through a variety of mechanisms, from Internet Relay Chat (IRC) and instant messaging to web browser extensions and DNS servers. Traditionally, first generation botnets have been structured around a client-server model that relies on one central server to communicate with each zombie computer. However, this architecture can be targeted by cybersecurity professionals and is susceptible to a single point of failure. Newer botnets are designed to be more resilient and harder to target. Many of these operate over Peer-to-Peer (P2P) networks, where each bot functions as both a command distribution server and a bot that receives commands. P2P bots discreetly probe random IP addresses until they contact another infected bot and share information, such as their software version.
While botnets can be spread by a variety of methods, phishing attacks remain the most prevalent initial infection vector. Users should always be cautious with email links and attachments, especially those that urge immediate action or create a sense of urgency. Update operating systems, applications, and firmware regularly and be sure to enable automatic updates whenever possible. Install a firewall to monitor outbound traffic, and use modern anti-malware tools that incorporate real-time protection, behavioral monitoring, and threat intelligence.