As one of the most common cyber threats, what type of program performs unwanted actions on a computer system, often causes damage, and requires an action (though usually unconscious) by the user to initiate it?

Spyware

Explanation:

A spyware is a software that is installed in a computer without the user's knowledge to steal information and monitor what he/she does like the things  that are downloaded and the websites that are visited. Also, a spyware can generate problems in the device like it becomes slow or crashes or it can run out of space. According to this, the program that performs unwanted actions on a computer system, often causes damage, and requires an action (though usually unconscious) by the user to initiate it is a spyware.