4. On the cloud side, there must be the following components: multiple virtual machines each with a separate anti virus engine installed, and a central monitor virtual machine that accepts file uploads (or monitors file uploads to S3), and then uses cloud services such as AWS Lambda to provide the file to the virtual machines with anti virus engines. The engines scan the file and sends report back to the monitor which combines the reports and sends the report back to the local engine, telling it if it is a virus/not a virus. Also, the blacklist or whitelist must be updated