How Does a Botnet Work?
A botnet is a network of computers or devices infected with malware that is controlled remotely without the users’ knowledge or consent. The infected machines, or bots, work together to execute various malicious activities, such as DDoS attacks, spam campaigns, and data theft. Many cybercriminals rent out these networks for profit through Botnet-as-a-Service or sell the malware to others.
Botnets can spread through phishing emails, software vulnerabilities, exploit kits in dark web marketplaces, and default passwords on routers and other IoT devices. They can also self-propagate using worm-like techniques. Users can help thwart attacks by always updating operating systems, applications, and firmware to patch known security vulnerabilities. They should also change default usernames and passwords on devices and limit remote access features.
After a device is infected, it communicates with a command and control (C&C) server to receive instructions from the botmaster. This centralized model is efficient for attackers but vulnerable to takedown efforts. More recent botnets use a peer-to-peer (P2P) architecture, making them harder to detect and disrupt.
Once the bots receive commands from the C&C infrastructure, they start their attack phase. Common tasks include launching DDoS attacks to flood target servers with traffic, stealing sensitive information from compromised devices, clicking on ads for click fraud, and spreading ransomware. Attackers can also use botnets to evade detection and perform cryptojacking. Security researchers and law enforcement track C2 servers, malware signatures, and infected devices to disrupt botnets. However, cybercriminals quickly rebuild botnets with new infrastructure and malware variants.