A conversation that comes up often concerns what rights a Windows Administrator (domain or local) has to folders and files. The common assumption is that being an Administrator is the backstage pass, but while it is somewhat true, the details are a bit more complex. Windows did not get to survive in the server space by oversimplifying security, but the defaults are quite open. The fact is that in most cases the Administrator will have rights to all files and folders, but that is not an innate right. It is more of a default circumstance that is very subject to change, especially in environments that have been around for a number of years.
The first thing to understand is that no user has inalienable rights to any file or folder. If an Administrator account or a group which the account is a member is granted no rights at all or is explicitly denied rights to a file or folder then the result will be Access Denied so long as that state persists. A single deny will override membership in a dozen groups with full control or even directly assigned full control. For mere mortal users that is game over, there is no way for them to change this situation without help. But here is where Administrator has a superpower. The key is that an Administrator has the ability to take ownership of any file or folder. This seems like a weak superpower, but it is in fact very powerful because once you own a file or folder, you can assign any permissions you like. This means that the deny can be removed or full permissions can be granted as needed to banish the Access Denied message. The root of this power is in the fact that the “Take ownership of files and other objects” user right in Local Security Policy defaults to giving this right to Administrators. Removing this right will allow permissions at the folder or file level to take precendence, but also removes the failsafe.
This mechanism has been around since Windows NT, but it has changed over the versions. Back in the early days an Admin could only take ownership for themselves, they could not assign ownership to any other user unless they logged in as that user. This meant that it would be hard for an Admin to take ownership, change permissions, read or edit something they should not be touching and then change permissions back and reassign the ownership to the original party. This changed several versions ago so that now Administrators can assign ownership since it must have been decided that the benefit of making ownership assignable outweighed the security of making the scenario from before more difficult.
Over time permissions get changed, often with the intent that the changes are temporary, but seldom does anyone find time to reverse these “temporary” changes to permissions. Sometimes blocking inheritance is part of the change and sometimes experiments become permanent. This all means that sometimes, even when you are logged in as an Administrator, you will see Access Denied. The key to overcoming this is understanding the way that being an Admin lets you access all files and folders. It is not as cut and dry as most people expect or would hope, but that is why it is secure.