Worm

A Worm is a self-replicating program that spreads to other computers by exploiting security holes. In other words, its like having a small hacker rendered completely in computer software and it hacks other computers on the internet and the uploads itself into the computer system that it takes over. Some payloads include making the infected system part of a Botnet which is a network of infected computers which can be used to create potent attacks on web services.