Trojan.Agent refers to a generic Trojan malware detection. It is used for detections that are either associated with no specific malware families or not enough information is available to pinpoint the malware family.
Backdoor.NJRat—a.k.a. Backdoor.Bladabindi, a.k.a. Derubsi—is a Remote Access Tool (RAT) which has been around for quite a while, yet is still very popular. We have seen some ingenious ways to spread it.
Malwarebytes can remove this RAT without further user interaction. However, users of affected machines should be aware of the fact that some or all of their credentials might have been compromised.