A botnet is a collection of internet-connected devices, such as computers, smartphones, and IoT gadgets, that have been infected with malware allowing a remote operator (called a botmaster) to control them. Each infected device becomes a 'bot' or 'zombie' and executes commands from a central server without the owner's awareness or consent.
Botnets typically form when malware spreads through phishing emails, compromised websites, unpatched software vulnerabilities, or weak passwords. Once installed, the malware connects the device to a command-and-control server where the attacker can issue instructions to thousands or millions of bots simultaneously.
Common botnet activities include:
- Sending spam emails and malicious links at scale
- Launching distributed denial-of-service (DDoS) attacks to overwhelm servers
- Mining cryptocurrency using victims' processing power
- Stealing personal data, passwords, and financial information
- Renting bot access to other criminals
The danger of botnets lies in their scale and invisibility. Owners often never realise their devices are compromised, and their machines become weapons against others. Large botnets can include hundreds of thousands of devices, making them powerful tools for criminals and state-sponsored actors.
To protect yourself: keep software and operating systems updated, use strong unique passwords, enable two-factor authentication, install reputable antivirus software, and be cautious of suspicious email attachments and links. Monitor your internet usage for unusual activity such as unexpected slowdowns or excessive data consumption, which may indicate bot infection.