I'm using VirtualBox 4.2.6 on Windows 7 host. I have Windows 2008 R2 guest using NAT.

My host uses IP address and is part of the domain. Guest is using two NAT adapters ( and

What is strange is that I can access \\\c$ network share from guest without passing any credentials!. I can't see any credentials cached both using:

C:\>cmdkey /list

Currently stored credentials:

* NONE *

and Control Panel\All Control Panel Items\Credential Manager:

enter image description here

can anyone tell me what's going on?

EDIT: tracert:

C:\>tracert -d

Tracing route to over a maximum of 30 hops

  1    53 ms    <1 ms    <1 ms
  2     1 ms     2 ms     1 ms

Trace complete.

EDIT: robocopy command

C:\>robocopy . \\\c$\_ test.txt

   ROBOCOPY     ::     Robust File Copy for Windows

  Started : Thu Jan 31 13:22:57 2013

   Source : C:\
     Dest : \\\c$\_\

    Files : test.txt

  Options : /COPY:DAT /R:1000000 /W:30


                           1    C:\
100%        New File                   0        test.txt


               Total    Copied   Skipped  Mismatch    FAILED    Extras
    Dirs :         1         0         1         0         0         0
   Files :         1         1         0         0         0         0
   Bytes :         0         0         0         0         0         0
   Times :   0:00:00   0:00:00                       0:00:00   0:00:00

   Ended : Thu Jan 31 13:22:57 2013

EDIT: net session /list

PS C:\Windows\system32> net session /list

Nazwa użytkownika       Administrator
Logowanie jako gość     Nie
Typ klienta
Czas bezczynności       00:00:58

Polecenie zostało wykonane pomyślnie.
  • what user are you logged in as on the VM? is there a local account on the host with the same username and password? there would be no stored credentials in that case. Check your local Administrator group membership (you need admin to hit $ shares). – Frank Thomas Jan 31 '13 at 12:49
  • That may be it. The guest is domain controller and I'm logged as domain administrator. But this virtual domain has not trust relation with the domain my host is member of... Does that mean that any administrator from any domain can access my \c$? – Grzegorz Grzybek Jan 31 '13 at 13:11
  • on the guest, connect to the host, and on the host, run this in powershell (as admin) to determine the user account being used: 'net session /list' – Frank Thomas Jan 31 '13 at 13:21
  • I've edited the question - it looks like it is local host's administrator... – Grzegorz Grzybek Jan 31 '13 at 13:46
  • so are both accounts named administrator and do they share a password? – Frank Thomas Jan 31 '13 at 14:34

Windows will automatically try any credentials tied to an interactive users account when authenticating to a remote PC over SMB, and will only ask for credentials if those it knows do not work.

in this case, the administrator user accounts exist locally, so when a user has an account on two machines that share a username and password, the user will not be prompted to authenticate.

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