RE: Encrypting Remote Files with EFS



Pat Hoffer [MSFT]
07-10-2005, 03:08 AM
Zack, were the servers at one time trusted for delegation? If so, you will
need to reboot the machines to clear EFS cache. EFS will cache up to 100
users' certificates (for performance). Users who had previously encrypted on
the servers would still be able to do so until the cache is cleared.

If the servers were never trusted for delegation, please give a few more
details. Exactly which client OSes (XPsp1, XPsp2, W2Ksp4, etc.) are able to
access which non-TFD servers (W2Ksp4, WS2003, WS2003sp1, etc.).

Thanks.
Pat
--
This posting is provided "AS IS" with no warranties, and confers no rights.


"Zack" wrote:

> We are in the midst of deploying EFS to protect specific folders on laptop
> hard drives. We want EFS used only for that purpose—locally; as such, we
> do not want users to have the ability to encrypt files that are residing
> on file servers. According to my understanding of EFS, which seems to be
> confirmed by the quote below from Windows help, users shouldn’t be able to
> do so unless we specifically enable file server(s) to be trusted for
> delegation in AD.
>
> “In a domain environment, remote encryption is not enabled by default. To
> enable encryption for a specific computer, your network administrator can
> make that computer trusted for delegation. For more information, consult
> your network administrator.”
>
> However, some of our servers are allowing files to be encrypted and
> decrypted remotely—and these servers are *not* marked as trusted for
> delegation in AD. Further, the user that encrypted the file can scoot
> over to another PC, log in as themselves, and access the file—and we have
> no CA infrastructure in place; these are locally-generated EFS
> certificates that do not chain back past the local client machine. The
> certificate thumbprints in the personal store for the user account on the
> two PCs do not match, yet they can access the file just the same, while
> other user accounts cannot.
>
> I’m thoroughly confused by this behavior, and would appreciate any experts
> chiming in and cluing me in as to why 1) some servers are allowing remote
> encryption, while others are not, and 2) why locally-generated EFS certs
> are behaving this way.
>
> Our environment:
>
> -Windows 2000 native-mode domain
>
> -All DCs are Win2k, file servers are a 2k/2003 mix
>
> -Clients are 2000/XP; the OS of the client/server doesn’t seem to matter—
> some 2k3 servers allow remote encryption, some don’t, and some 2000
> servers allow, while others don’t.
>
> Thanks,
>
> -Zack-
>

Pat Hoffer [MSFT]
07-10-2005, 03:08 AM
Just to clarify, only the servers would need to be rebooted.

Thanks.
Pat
--
This posting is provided "AS IS" with no warranties, and confers no rights.


"Pat Hoffer [MSFT]" wrote:

> Zack, were the servers at one time trusted for delegation? If so, you will
> need to reboot the machines to clear EFS cache. EFS will cache up to 100
> users' certificates (for performance). Users who had previously encrypted on
> the servers would still be able to do so until the cache is cleared.
>
> If the servers were never trusted for delegation, please give a few more
> details. Exactly which client OSes (XPsp1, XPsp2, W2Ksp4, etc.) are able to
> access which non-TFD servers (W2Ksp4, WS2003, WS2003sp1, etc.).
>
> Thanks.
> Pat
> --
> This posting is provided "AS IS" with no warranties, and confers no rights.
>
>
> "Zack" wrote:
>
> > We are in the midst of deploying EFS to protect specific folders on laptop
> > hard drives. We want EFS used only for that purpose—locally; as such, we
> > do not want users to have the ability to encrypt files that are residing
> > on file servers. According to my understanding of EFS, which seems to be
> > confirmed by the quote below from Windows help, users shouldn’t be able to
> > do so unless we specifically enable file server(s) to be trusted for
> > delegation in AD.
> >
> > “In a domain environment, remote encryption is not enabled by default. To
> > enable encryption for a specific computer, your network administrator can
> > make that computer trusted for delegation. For more information, consult
> > your network administrator.”
> >
> > However, some of our servers are allowing files to be encrypted and
> > decrypted remotely—and these servers are *not* marked as trusted for
> > delegation in AD. Further, the user that encrypted the file can scoot
> > over to another PC, log in as themselves, and access the file—and we have
> > no CA infrastructure in place; these are locally-generated EFS
> > certificates that do not chain back past the local client machine. The
> > certificate thumbprints in the personal store for the user account on the
> > two PCs do not match, yet they can access the file just the same, while
> > other user accounts cannot.
> >
> > I’m thoroughly confused by this behavior, and would appreciate any experts
> > chiming in and cluing me in as to why 1) some servers are allowing remote
> > encryption, while others are not, and 2) why locally-generated EFS certs
> > are behaving this way.
> >
> > Our environment:
> >
> > -Windows 2000 native-mode domain
> >
> > -All DCs are Win2k, file servers are a 2k/2003 mix
> >
> > -Clients are 2000/XP; the OS of the client/server doesn’t seem to matter—
> > some 2k3 servers allow remote encryption, some don’t, and some 2000
> > servers allow, while others don’t.
> >
> > Thanks,
> >
> > -Zack-
> >


RE: Encrypting Remote Files with EFS