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 uses custom packers to obfuscate their code. This concerns packers that are normally not in use for legitimate purposes. So the detection is purely based on the way the file is packed and the payload could be anything.
Malwarebytes protects users from Trojan.Malpack by using real-time protection.
Malwarebytes can detect and remove Trojan.Malpack without further user interaction.