Computer worm
A computer worm is malicious software that copies itself between computers, typically across networks, without attaching itself to another program.
Vulnerability: A weakness in software, hardware, or configuration that can be exploited to compromise a system. Worms often exploit vulnerabilities to enter computers and continue spreading.
Computer virus: Malicious code that replicates by attaching itself to a host file, program, or other object. Unlike a worm, a virus depends on a host and usually spreads when that host is run or shared.
Morris worm: A 1988 internet worm that exploited Unix systems and disrupted thousands of computers. It demonstrated how rapidly networked self-replication could disrupt systems, even without a destructive payload.
Computer security: The protection of computer systems, networks, and data from unauthorized access, damage, or disruption. Worm prevention and response are central problems in protecting connected systems.
Denial-of-service attack: An attack that makes a computer or network service unavailable by overwhelming or disrupting it. A rapidly replicating worm can congest networks or help generate denial-of-service traffic.
Exploit: Code or a technique that takes advantage of a vulnerability in a computer system. An exploit can automate the entry that lets a worm infect another computer.
Trojan horse (computing): Malicious software disguised as legitimate or useful software to induce installation or execution. A Trojan relies on deception and does not necessarily reproduce itself.
ILOVEYOU: A 2000 email-borne malware outbreak that spread through a Visual Basic script posing as a love letter. Its rapid spread illustrates how worms can combine replication with a compelling social lure.
Patch management: The process of acquiring, testing, and deploying software updates to fix defects and vulnerabilities. Timely patches close weaknesses that worms may exploit to enter systems.
Critical infrastructure: Systems and services essential to society, including energy, water, communications, and transportation. Worms that reach industrial networks can threaten services beyond ordinary computing.