Re: Windows Media Player executes WMF content in .MP3 files.

From: Will Packard (will@nortelnetworks.com)
Date: 03/01/02 

From: Will Packard <will@nortelnetworks.com>
Date: Fri, 01 Mar 2002 17:24:39 -0500

Alun Jones wrote:
>
<snip>
> Yes. This is my point. The Unix kernel (and I apologise for using the word
> "shell" above, when it is, as you say, the kernel that makes this decision)
> does the same thing that people are upset about Windows Media Player doing.
> It _ignores_ the file name completely, extension and all. It chooses how to
> run the file by checking its magic number - i.e. the file's _content_.

I think the part of this discussion that's eluding you, is the fact that
filenames have *always* been irrelevant in Unix, whereas file "extensions"
have traditionally had meaning in Windows (and DOS before that, and CP/M before
that, and...). Double-clicking on an icon should have a consistent behaviour
on a given platform. If the platform traditionally uses extensions to determine
file type, it should *always* do this.

> Just the same way that Media Player ignored the file name, and used the file's
> content to determine to play it as a WMV file.

Which is contrary to traditional behaviour on that platform.

<snip>
> Only when the user is misled by some other means already. If I see a file
> "fred.txt", I cannot easily get the operating system to run it, even if it is
> simply "fred.exe" renamed. Double click it, and I get Notepad, and only
> Notepad. Double clicking a file with a .MP3 extension will cause the MP3
> application to open, and that file to be opened within the application. If
> that application then chooses to play it as a video, or some other form, it is
> because the application, not the operating system, has checked the content and
> made that decision.

Thanks to tradition, Windows users are easier to socially engineer, even if
they later use another OS. They've been taught for years that *.txt must be
a text file, etc. When someone (not necessarily Microsoft) then writes an
application which ignores the file type, and treats the file by content,
the user is fooled. In general, regardless of OS, GUIs display an icon which
corresponds to how the system will treat the file, whether the filename is
significant or not.

<snip>
> Here's the point - when users are led to believe that the extension defines
> the content, even in a situation where one application is responsible for
> handling several different kinds of content, those users can get confused.
> Just as in a Windows environment, Media Player handles files with the
> extensions MP3, WMV, etc, etc, and operates on the content ignorant of the
> extensions, so too in a Unix environment, the kernel handles files that are
> executable, and operates on the content ignorant of the extensions.

True. This is why, even when people move up to Unix/Linux/etc., they can be
fooled into thinking that the filename is important, when it is not.

> Extension-renaming is behind a number of web-based vulnerabilities, ISTR,
> requesting a file and tacking an extension on to the end in a manner not
> properly handled by the server. This is yet another of such exploits, and
> such exploits are not necessarily specific to Windows, but to any environment
> where a user expects the file name to determine what action is taken on the
> file contents.

True. Of course, between Windows, Mac and Unix, Windows is the only OS
which assigns special meaning to filenames. "FILENAME FILETYPE FILEMODE"
and "FILENAME.EXT" are concepts that should have died with the mainframe
era, IMHO. I suppose I could say the same for CP/M's A:, B:, C:...

HTH,
Will

Relevant Pages

  • Re: 100% Linux - Is it possible?
    ... Unix, by and large, doesn't use file extensions enough to matter. ... Windows is sufficiently set in its ways that it occasionally needs ... But, unfortunately, while there are Windows programs out there that ...
    (Fedora)
  • Re: Migrating Matlab files from Windows to UNIX
    ... distinguish \ between part of a filename r a dir sep. ... But Matlab could have prevented this. ... One company wanted a Windows version, ... others wanted on UNIX. ...
    (comp.soft-sys.matlab)
  • Re: Migrating Matlab files from Windows to UNIX
    ... distinguish \ between part of a filename r a dir sep. ... One company wanted a Windows version, ... others wanted on UNIX. ... expect software to conform to the standards for that platform. ...
    (comp.soft-sys.matlab)
  • Re: Migrating Matlab files from Windows to UNIX
    ... Michael Wild wrote: ... distinguish \ between part of a filename r a dir sep. ... One company wanted a Windows version, ... others wanted on UNIX. ...
    (comp.soft-sys.matlab)
  • Re: Windows Media Player executes WMF content in .MP3 files.
    ... The Unix kernel (and I apologise for using the word ... >> does the same thing that people are upset about Windows Media Player doing. ... If the platform traditionally uses extensions to determine ... >file type, ...
    (comp.security.misc)
Loading