Also known as a zombie army, a botnet is a collection of internet-connected devices that an attacker has compromised. These botnets can try to infect more computers or spread spam for affiliate fraud, amongst other reasons. They can also act as a proxy to mask a criminal’s original IP address. Botnets mainly act as a force multiplier for individual attackers, cyber-criminal groups and nation-states looking to disrupt or break into their targets’ systems. Commonly used in distributed denial of service (DDoS) attacks, botnets can also take advantage of their collective computing power to send large volumes of spam, steal credentials at scale, or spy on people and organizations.