A cyber-attack is an assault launched by cybercriminals using one or more computers against single or multiple computers or networks. A cyber-attack can maliciously disable computers, steal data, or use a breached computer as a launch point for other attacks. Cybercriminals use a variety of methods to launch a cyber-attack, including malware, phishing, ransomware, denial of service, among other methods.

A cyber-attack may steal, alter, or destroy a specified target by hacking into a susceptible system. Cyberattacks can range from installing spyware on a personal computer to attempting to destroy the infrastructure of entire nations. Legal experts are seeking to limit the use of the term to incidents causing physical damage, distinguishing it from the more routine data breaches and broader hacking activities. Cyberattacks have become increasingly sophisticated and dangerous.