Which type of malware is designed to replicate itself and spread to other devices?

The type of malware designed specifically to replicate itself and spread to other devices is a worm. Worms are a category of malware that can independently propagate through networks. Unlike viruses, which often require a host program or a user to execute them, worms exploit vulnerabilities in software or operating systems to replicate themselves without needing any user intervention. This characteristic allows them to quickly infect numerous systems by leveraging network connections, making them particularly dangerous in the realm of cybersecurity.

In contrast, spyware is designed to gather information from a user's device without their consent, often to track online activities and gather personal data. Trojan horses masquerade as legitimate software to trick users into executing them but do not inherently possess the ability to replicate itself or spread on their own. Rootkits, on the other hand, are tools used to hide the existence of certain processes or programs from normal methods of detection, often used to maintain unauthorized access to a system. While all these types of malware can be harmful, only worms are characterized by their self-replication and spreading abilities.