I am thinking these are executable files of some type, with a fake extension, so they look like a .doc or .pdf.
Typically, Outlook will hide the real extension, so all you see is the fake icon and fake extension.
only if the program that the icon belongs to is installed on the system.
there is no default "word" icon in the OS. when you install word, it creates a registry entry that says that anything with a .doc extension will be opened with word and use the word icon from the relevant .dll file that is part of word.
Yes, so it is likely that an .exe file will not show the Word-icon (fake icon) and thus not confuse anybody (or less people).
But I suppose it is possible to confuse the OS.
well, if the exe has a dll file in it that falsely says to use the word icon I think it could work that way.
but I am not sure. the hackers are much smarter than me.
I just know that in over 30 years of working on computers I have only had a virus twice. both times while I was running without anti virus programs for a short time.
I never did put floppies in that I did not know where they came from, I never have opened email attachments that I am not sure about etc.
common sense will keep you from having a problem in 99% of the time.