Networks & Defense
Worm
Also: computer worm, self-propagating malware
Malware that copies itself to other machines automatically, without anyone running it.
In more detail
A worm finds reachable machines, usually by scanning for a vulnerable service or weak credentials, infects them, and repeats from each new host. Because the spread is automatic, the number of infected machines grows exponentially. Patching, removing unneeded services and segmentation all slow it. The same pattern appears in software supply chains, where a stolen publish token lets a worm publish itself into further packages.