Rather than relying on the file name alone, Trend Micro NAS Security™ uses IntelliScan to identify the true file type, and whether it is a type that Trend Micro NAS Security™ should scan.
True
file-type detection: IntelliScan first examines the header of the
file using true file-type identification and checks if the file is an
executable, compressed, or other type of file that may be a threat. IntelliScan
examines all files to be sure that the file has not been renamed
File extension checking: IntelliScan also uses extension checking. The list of extension names to be scanned is updated with each new pattern file. For example, when a new .JPG vulnerability is discovered, the ".jpg" extension will be immediately added to the extension-checking list for the next pattern update.