To detect the file type of user submitted file, exif must be enabled in PHP.
To enable exif-support configure PHP with --enable-exif
Windows users must enable both the php_mbstring.dll and php_exif.dll DLL's in php.ini. The php_mbstring.dll DLL must be loadedbefore the php_exif.dll DLL so adjust your php.ini accordingly.
Note: There is no options in wordpress to do it. It is service side issue.