Acción producida en el ciberespacio que compromete la disponibilidad, integridad y confidencialidad de la información mediante el acceso no autorizado, la modificación, degradación o destrucción de los sistemas de información y telecomunicaciones o las infraestructuras que los soportan.

O.M. 10/2013, de 19 de febrero, por la que se crea el Mando Conjunto de Ciberdefensa de las Fuerzas Armadas

Uso del ciberespacio para atacar a los sistemas y servicios presentes en el mismo o alcanzables a través suyo. El atacante busca acceder sin autorización a información, o alterar o impedir el funcionamiento de los servicios.

An attack, via cyberspace, targeting an enterprise’s use of cyberspace for the purpose of disrupting, disabling, destroying, or maliciously controlling a computing environment/infrastructure, or for destroying the integrity of the data or stealing controlled information. [US-ESC:2012]

An attempt to undermine or compromise the function of a computer-based system, access information, or attempt to track the online movements of individuals without their permission. [CSS NZ:2011]

A cyber attack is an IT attack in cyberspace directed against one or several other IT systems and aimed at damaging IT security. The aims of IT security, confidentiality, integrity and availability may all or individually be compromised.[CSS DE:2011]

An act or action initiated in cyberspace to cause harm by compromising communication, information or other electronic systems, or the information that is stored, processed or transmitted in these systems.

is an offensive use of a cyber weapon intended to harm a designated target.

Russia-U.S. Bilateral On Cybersecurity Critical Terminology Foundations, Apr. 2011.

An attack, via cyberspace, targeting an enterprise’s use of cyberspace for the purpose of disrupting, disabling, destroying, or maliciously controlling a computing environment/infrastructure; or destroying the integrity of the data or stealing controlled information. [CNSSI_4009:2010]