Computer worm

A computer worm is a type of malware ✕ Malware (from "malicious software") is the umbrella term for any harmful software — viruses, trojans, ransomware, spyware — that damages, spies on, or hijacks devices. More in the glossary → that replicates and spreads on its own across networks, exploiting security flaws, without the user having to open a file or run a program. That is its big difference from a virus, which needs to attach to a file and have someone open it: the worm travels from machine to machine autonomously and can infect entire networks in little time. Along the way it consumes bandwidth ✕ Bandwidth is the amount of data that can be transferred per second over a connection. More bandwidth means faster downloads and smooth streaming. More in the glossary → , slows systems and often installs other threats or opens backdoors. The defense is to keep the system and apps updated —to close the holes it exploits— plus a firewall ✕ A firewall is a protective barrier between your device or network and the internet. It monitors data traffic and blocks unwanted or dangerous connections. More in the glossary → and a good antivirus ✕ An antivirus is a program that detects, blocks and removes malicious software. Modern ones combine known signatures with behavior analysis. More in the glossary → . More in the best antivirus comparison.