When trying to activate the operating system, a user receives a notice that the software is not genuine. Which of the following security threats has occurred?

Social engineering involves manipulating people to divulge information or perform actions, not directly related to software activation validation.

Phishing is a type of social engineering that attempts to acquire sensitive information by impersonating a trustworthy entity, which is not the cause of a "not genuine" activation message.

A virus attack refers to malicious software infecting a system, which might cause various issues but is not the primary reason for an operating system to be flagged as "not genuine" during activation.

When an operating system activation fails with a "not genuine" notice, it signifies that the software's license key or activation method is not validated by the manufacturer, indicating unauthorized usage. This directly constitutes license theft, as the user is attempting to operate the software without a legitimate, purchased license.