scareware
noun
A type of attack designed to scare or scam users into installing or purchasing malicious software by convincing them falsely that their computers are infected with malware, and that the malicious software will remedy it. Scareware can also be used for direct extortion, by convincing someone, for example, that the attacker has compromised their webcam and has thereby obtained embarassing images of the victim. In all cases scareware falsely pretends to have obtained information or performed some action that in fact the attackers have not gotten or done. Compare sextortion.
noun
A type of malware designed to scare or scam users into installing or purchasing malicious software by convincing them that their computers are infected with malware, and that the malicious software will remedy it.