Botnet

A network of compromised computers or internet-connected devices that are secretly controlled by an attacker and used together to send spam, steal data or launch attacks.

Each infected device in a botnet is called a bot. Owners usually have no idea their equipment is involved. Botnets can include office computers, home routers, security cameras and other smart devices. The attacker, sometimes called the bot herder, sends instructions to the whole network at once.

For a small business, a botnet matters in two ways. First, your own devices could be recruited, using your internet connection and potentially getting your IP address blocked or your email flagged as spam. Second, botnets power many of the attacks you may face, including password-guessing campaigns, large spam runs and distributed denial-of-service attacks against websites.

Practical tip: change default passwords on routers, cameras, printers and other connected devices, keep their firmware updated, and replace equipment that no longer receives updates. Unusual network slowdowns or a sudden spike in outbound traffic are worth reporting to your IT provider.