Botnet
A network of malware-infected computers ('bots') controlled remotely by a criminal to carry out coordinated attacks such as spam campaigns, DDoS attacks, or credential stuffing.
Also known as: zombie network, bot network
Last reviewed: 1 June 2026
A botnet is a collection of internet-connected devices that have been infected with malware and are under the coordinated control of an attacker (the 'bot-herder'). Individual infected devices, called bots or zombies, typically show no obvious signs of compromise.
Botnets are used to send spam and phishing emails at scale, conduct distributed denial-of-service (DDoS) attacks, perform credential-stuffing attacks against websites, mine cryptocurrency using the victims' processing power, and distribute further malware.
Device owners unknowingly contribute their computing resources and internet bandwidth to criminal operations. Routers, smart-home devices, and poorly secured IoT devices are increasingly recruited into botnets in addition to traditional computers. Keeping all devices patched and using network firewalls reduces the risk of recruitment.