A network browser has a Malware detection manager for direct or indirect scanning of files during an upload or download processes for viruses, adware, spyware, etc. The malware detection manager defines and employs a quarantine bin, which is an isolated and secure memory space or directory for temporary placement of file packets during the file transmission while malware detection can commence. The malware detection manager scans for any malware code associated with the packet sequence encountered during a file transmission to and from the Internet, during which it quarantines all the scanned packets in the quarantine bin. Quarantined files can be released if there is a human challenge authorizing the release of the file. The invention also comprises exchanging a Malware free signature between server and client via a trusted download center. If a certified and valid malware free signature is provided, the client device need not scan the files for malware bytes as the content is certified and guaranteed as malware-free.