An employee has reported that their computer has been performing unusually, including slow response times and unknown processes running in the background. After further investigation, you find a suspiciously named service installed that allows remote connections and control over the system, even though no such software was authorized or installed by the IT department. Based on these indicators, what type of malware is MOST likely present on the employee's computer?
Rootkit
Remote access Trojan (RAT)
Adware
Spyware