A self-replicating, self-propagating, self-contained program that uses networking mechanisms to spread itself.
From: CNSSI 4009.
Source: NICCS™ Portal Cybersecurity Lexicon, National Initiative for Cybersecurity Careers and Studies (https://niccs.us-cert.gov/glossary) as of 11 November 2015, Global Standards
Computer program that can run independently, can propagate a complete working version of itself onto other hosts on a network, and may consume computer resources destructively .
Source: ANSI/ISA–99.00.01–2007, Security for Industrial Automation and Control Systems, Part 1: Terminology, Concepts, and Models, 29 October 2007. National Standard