Help - Writing Web Control to Access the Local FileSystem

[Nigel]

Hi,

We have a need to write a web control that access the local filesystem
and creates a set of hyperlinks based on the files contained within a
directory (this will then be used in a sharepoint web part).

Don't know a lot about this stuff, but have written an ActiveX control
that, when used on a Windows form, works correctly, however when used
on a web application gives the following error:

Request for the permission of type
'System.Security.Permissions.FileIOPermission, mscorlib,
Version=2.0.0.0, Culture=neutral, PublicKeyToken=xxxxxxxxxx' failed.

Can anyone explain what is happening here, and how I resolve this
issue?

Not knowing alot about this, I am not sure if this approach is the best
one. If anyone has ideas about other (better) ways that we could
achieve this, please let me know.

Many Thanks,

Nigel

[Marc Gravell]

welcome to the sandbox.

I'm not a web-OCX guru, but I suggest that this could cause huge
security issues, allowing (depending on the features exposed) random
pages (e.g. intranet?) to exploit your control to browse any user's
file system. I suggest you take a look at:
http://msdn.microsoft.com/msdnmag/issues/02/06/rich/ (search for the
phrase "File system access is the big one").

There may be some solutions involving signing the code with a a valid
(chained) certificate and assigning the required permissions (not
ideal, as not very site-specific), or possibly trusting the site
(worse) - or maybe some caspol hacks...

No simple answer for you, though

Marc