Severe threats typically are remotely exploitable vulnerabilities, which can lead to system compromise. Successful exploitation does not normally require any interaction and exploits are in the wild. There exists a high possibility of potential system damage or security flaw. Attacker has complete control over your computer or install new software on your machine.
Key Logger - A Trojan software is any software on a user's computer that the user is not aware or intentionally installed. Most Trojan software is designed to perform some sort of actions that could jeopardize the user's security or privacy.