Malware. is a category name for malicious software that has not been categorized more precisely. Malwarebytes uses the underlying categories:
Generally speaking, detections categorized as Malware. will be examined by researchers and put in a category that better describes their behavior.
Malwarebytes detects unknown threats as Malware. by using heuristics, Artificial Intelligence, Machine Learning, and generic detection rules to protect users from malware that has not yet been researched and classified.