Jtdylktuy

I somehow botched up my C: (root folder) security settings on Windows 10. They remained botched even after an in-place reinstall and somewhat botched after a full (no-save) reinstall. Right now if I add a folder to C: from a (user) command prompt I get "access denied", but from Windows explorer I get four copies. This is weird but true. Here's a screenshot:

I don't know how to reset these security settings properly, although I have examples from another virtual machine as to what they should be. Experimenting using the Windows explorer security properties information on a virtual machine, anything I add or subtract seems to be applied recursively.

I haven't tried using the icacls command as the sparse documentation on it doesn't really explain what the options really do. It's not clear from its documentation how or even whether this command relates to security properties.

So, what procedure do I use to update the C: (root) folder permissions but only that folder's permissions?

Your screen shot shows a number of Deny entries. Remove these. They're not part of the default permissions for the root of a volume and are certainly causing you trouble.

For your reference, here are the default permissions for the root of a boot volume on Windows 10:

Try to get your permissions to match these.

Edit: More detail on how to effect these changes.

Caution: For the root folder, NEVER click on propagate changes to all subfolders. Many subfolders have been given different security attributes that you don't want to change.

Warning: Make sure you have a backup plan in case this procedure fails. You may need to reinstall if something goes wrong.

1) In order to change the permissions, you need to take ownership. Click on the Blue change for the owner, and change the owner to Administrators. This is also for protection: Even administrators are not allowed to modify some subfolders.

2) Remove the Deny entries.

3) For the entries you are going to keep, make sure their permissions are set properly, using the advanced menu. For windows 10, you need to update BOTH the basic and advanced settings. The proper settings are detailed below.

4) Delete the other entries.

5) Apply the changes, and cross your fingers. You should get warnings that your changes did not propagate to some Windows owned subfolders and swapfile.sys.

6) Change the owner back to TrustedInstaller, whose actual name is "NT ServiceTrustedInstaller".

Permissions detail:

Administrators, Full control, This folder, subfolders and files

Full control: All boxes in basic and advanced permissions should be checked.

SYSTEM, Full control, This folder, subfolders and files

Full control: All boxes in basic and advanced permissions should be checked.

Users, Read & excute, Subfolders and files only

Basic: Only Read&execute, List folder contents, Read

Advanced: Only

    Traverse folder / execute file

    List folder / read data

    Read attributes

    Read extended attributes

    Read permissions

Authenticated Users, Modify, Subfolders and files only

Basic: Only Modify, Read&execute, List folder contents, Read, Write

Advanced: Only

    Traverse folder / execute file

    List folder / read data

    Read attributes

    Read extended attributes

    Create files / write data

    Create folders / append data

    Write attributes

    Write extended attributes

    Delete

    Read permissions

Authenticated Users, Create folders / append data, This folder only

Basic: NONE

Advanced: Only Create folders / append data

I have only access to a Windows 7 Pro machine at the moment, but I have seen that it's the same in later Windows versions (but please note that the UI might slightly differ):

The advanced dialog for changing permissions offers a drop-down box in its upper area, offering to apply the permissions to this folder, subfolders and files, files only and so on.

Furthermore, in the lower area of that dialog, there is a checkbox titled Apply these permissions to objects and/or containers within this container only.

You can see what I mean on the following screenshot:

Unfortunately, you need to look at the problem from the perspective of the child folders as well. For example, if you have a folder c:parentchild, and the child folder already inherits permissions from the parent folder, and you want different permissions in the parent and child folders, you first must disable the permission inheritance for the child folder.

You can do so at the following place (please note the checkbox labeled Include inheritable permissions from this object's parent):

I hope this answers your question.