Which type of malware can propagate on its own without a host application?

Worms are a type of malware that can self-replicate and propagate independently, without the need for a host application. This capability allows worms to spread across networks and systems automatically, often exploiting vulnerabilities in software or network services to initiate their propagation. Once a worm infects a system, it can use that system to scan for other hosts, further spreading itself without any user intervention or files to act as a carrier.

In contrast, other types of malware such as malicious scripts, Trojan horses, and ransomware typically require a host application or some form of user interaction to initiate their actions. Malicious scripts often rely on execution through a particular program or browser, Trojan horses disguise themselves as legitimate applications, and ransomware generally requires some interaction from the user to be deployed. Thus, worms are unique in their autonomous capability to spread without needing a host.