Share, subdirectory permissions and pass-through
Posted on 2013-11-07
Hello everyone. I've come across something a little strange. This came up accidentally, but it opened my eyes to some possible problems.
Due to the strange nature of our data, folder structure and employee permissions, I use file-based access permissions (using groups, of course) to allow or deny people access to certain shares, areas within those shares, and specific subfolders sometimes up to three or four levels down. So far I have never used the DENY permission anywhere.
I generally give all our employees a SHARE-level access of full control. I use a special group for this, and not the "everyone" group. Since I control all file-level permissions and allow or deny there, I never thought this would be a big problem.
I recently discovered the following.
Share permission: All Employees - Full Control
Base directory: No explicitly defined access for a specific user. Just Server\Administrators, and Information Technology.
First subdirectory: Again, no explicit permission
First\Second subdirectory: Same Thing
First\Second\Third subdirectory: This one user has read access.
By specifying a path of \\Server\Share\First\Second\Third, they are able to see the contents of this directory.
I initially though this was because I was using a NAS or got the permissions wrong, but after doublechecking and testing this on a Server 2008 R2 and Server 2012 machine, I get the same results.
I tried setting the permissions on the SECOND directory to explicitly DENY this individual user access to the SECOND directory (no further inheritance). Looked at the advanced permissions, they are Denied everything. They can still get through to the ...\three subdirectory.
Am I missing something here? If someone doesn't have any permission to a directory, subdirectory, have specifiy DENY permission to a third, how can they pass through all of them to get to a directory where they DO have permission?
I'm aware this is strange and not something that should normally happen. How would they even know the directory names to get to this subdirectory? However due to some odd lunar alignments and my good luck, this has come to light.
If anyone could explain this to me, and also let me know a good way to prevent this from happening in the future, I'd really appreciate it. Are there any other hidden fun things like this I should know about?
I'm already thinking about changing share permissions and directory structure.
Unfortunately, IT control of the share/directory structure is somewhat limited.
We recently used DFS (not replication) to merge many shares into a company-wide standard directory structure without actually running amok and changing the share contents. To be honest, some of the shares are somewhat ... non-intuitive?
Creating a new permission/directory/share structure isn't a challenge I'm looking forward to.