What is worm?

Worm (Worm) is a distributed network to spread specific information or errors, and thus cause network services to be rejected and deadlock.
In 1982, Shock and Hupp proposed The idea of a Worm program based on a concept in The Shockwave Rider book.

This "worm" program is resident on one or more machines and has the ability to automatically reposition (autorelocation. If it detects that a machine in the network is not in use, it sends a copy of itself (a program segment) to that machine. Each program segment can relocate its own copy on another machine and identify which machine it occupies.

Worms are not necessarily harmful. It demonstrates that the worm program can be used as a diagnostic tool for Ethernet network devices. It can quickly and effectively detect networks.

A worm consists of a master program and a Bootstrap program. Once the main program is established on the machine, it will collect information about other machines connected to the current machine. It can achieve this by reading the public configuration file and running the system utility that displays the online status of the current network. Then, it tries to use the defects described above to build its boot program on these remote machines.

It is this small program, usually called a boot program or a phishing program, that brings the worm into every machine it is infected.