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.
This is a generic detection for Trojans that are present on affected systems as altered Microsoft files. Thus, the files will be signed by the actual Microsoft Corporation but are no longer the original files. A malicious payload will have been added to the file.
Malwarebytes can remove the threat without further user interaction. It can not always replace the file with the original, so users may want to run the Windows System File Checker after the removal has been completed.