Windows fileserver (FSRM) file screening and offline files
Posted on 2014-10-30
We have a fileserver where everybody's My Documents, Downloads, Desktop etc. folders are redirected. The fileserver is running Windows Server 2012 R2, and is running the File Server Resource Manager role.
I've set up file screens that prevent the users from saving executable files into their user profiles. This is to help dissuade users from accidentally downloading malware / spyware / junk from the Internet. I also block them from saving documents to their desktop (only shortcuts / links can go on the desktop).
And for the most part, it works. If I attempt to use any Microsoft product to save any disallowed files (e.g. File Explorer, Internet Explorer, Word etc.), I get an appropriate error box saying access is denied and it blocks it.
But under certain circumstances (e.g. downloading EXE files in Google Chrome), the EXE is still downloaded and they appear to be saved into the folder.
I've discovered that what is going on is that the folders have offline file caching turned on, and because of this the file gets cached in the offline mode on the one computer. The bad files never arrive on the server, but their computer caches it forever, and Windows periodically tries to sync it up to the server (and fails). The user doesn't realize that the file is in this "transient" state, and they think they've successfully saved a file when really they haven't, but regardless they can ACCESS the file as if it was saved directly into that folder, which defeats the purpose of the file screens.
I have email notifications configured on the Fileserver to tell me when violations to the file screening rules occur, and I am getting INUNDATED with hundreds of notifications every day for the same couple files on a couple user's machines every time the Windows Sync center fails to sync the offline file over and over again.
I'm not sure what to do about this...
For the users who already have offline cached files that are stuck on their system, is there a way to purge the cache so those files go away?
And is there a way to configure the workstations to be more strict about not allowing EXE files to be saved to their redirected user profiles?