How to require and ensure program has admin priv to launch, and can delete a hidden file?

Question

Hello fellow developers,

I'm trying to give a C# application that I'm creating the ability to delete the files from a flash-drive or other folder, for which admin priv is needed. But it's not working!

I am an admin user on my Win10 box. I can delete the files in File Explorer. But the program throws an IOException when it tries to do it (I'm using any of several methods to delete the files, including interoping to Win32).

I did create and embed an Application Manifest for the program project (I'm using Visual Studio 2017), and set the level attribute of the requestedExecutionLevel element to "requireAdministrator". And within the project-properties it does show this file, app.manifest, as part of it. But that seems to accomplish nothing -- the program can still be launched NOT as administrator.

Btw, I see two different methods to detect whether the program is running as with administrator priv:

public bool IsRunAsAdmin1()
{
    return Thread.CurrentPrincipal.IsInRole( WindowsBuiltInRole.Administrator.ToString() );
}

This does NOT seem to be working (always returning false). and..

   public bool IsRunAsAdmin2()
    {
        WindowsIdentity id = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal( id );
        return principal.IsInRole( WindowsBuiltInRole.Administrator );
    }

which does work.

Regardless, even when I right-click on the program and run it as administrator -- it returns Win32 error 5 (access denied) for Hidden files.

I want to make this delete files robustly, regardless of the file's attributes. How can I do this?

Thank you for your help and insights, James

All you can do is to tell users to "Run as administrator". You can't program-in this. It will make viruses spread like hell — T.S., Aug 04 '17 at 19:28
Take a look at System.Security.Permissions.FileIOPermission. If they are in the administrator role, they should be able to demand "AllAccess," and then do what they need - I believe even if the program isn't started with "Run as admin" (I use it in prod without issue - my guys never start with "Run as")... (Note - we don't delete hidden - worth a test though) — Aaron, Aug 04 '17 at 20:02

score 0 · Answer 1 · answered Aug 06 '17 at 10:10

I'm not sure what do you mean by

the program can still be launched NOT as administrator.

If you setup the app.manifest file properly (see this) then it always will be running as administrator.

I'm not sure about the hidden files. My quick advice would be just to remove the hidden/readonly flag (like this) and then call File.Delete.

How to require and ensure program has admin priv to launch, and can delete a hidden file?

1 Answers1