Systems, methods and apparatus for malware detection to detect and stop the distribution of malware and other undesirable content before such content reaches computing systems. A Malware Detection Service (MDS) including a processor and memory storing computer program instructions that when executed cause the processor to receive one of content or a signature of a file, responsive to receiving a signature of a file, determine a status of the file as trusted, untrusted, or unknown for malware based on the signature, responsive to receiving content of a file, generate a signature of the file and scan the content to identify the status of the content as trusted or untrusted.