Article detailing how malware can blend into your computer system by changing its file association.
File association
File association is the method by which a file icon is associated to a file extension. This includes what program is to be used to open that particular file type. Again these are methods malware can use to hide in plain sight.
File association are located within the HKCR registry hive. The hive contains the file extensions and any associated programs used to open those file extensions.