What is a Botnet?
A Botnet is a network of computers, servers or IoT devices infected with malware that is controlled by cyber criminals, known as bot herders. These individuals or groups use botnets to carry out large-scale cyberattacks for financial gain, or as a way of getting recognition in hacker communities. While the victim remains unaware of their infection, the bot malware operates in the background to perform attacks, following instructions from the bot herder’s command and control server (C2) or through a decentralized peer-to-peer system.
Cybersecurity professionals must recognize early warning signs of botnet infection to protect networks and data. These indicators often appear as subtle performance issues, such as slow-than-normal application response times and sluggish applications. Unexplained programs that crash, unusual RAM usage, and a sudden increase in network traffic are other signs of a compromised device.
Most first generation botnets operate on a client-server model, with one C&C server operating the entire botnet. The clients communicate with the C&C server using Internet Relay Chat (IRC) and receive commands in the form of normal chat messages. This type of botnet is simple to set up and run, but has a major drawback: If the C&C server is discovered or disabled, all the infected devices become unresponsive.
Newer botnets operate over P2P networks, with each bot acting as both a server that distributes commands and a client that receives them. This design reduces the risk of a single point of failure, but increases the latency for data transmission between bots. More advanced bots may log keystrokes, monitor user activity, or steal login credentials to access online accounts and websites. This information can then be used for DDoS attacks, spamming or ransomware attacks.