Network Authentication when running exe from WMI

Question

I have a C# exe that needs to be run using WMI and access a network share. However, when I access the share I get an UnauthorizedAccessException. If I run the exe directly the share is accessible. I am using the same user account in both cases.

There are two parts to my application, a GUI client that runs on a local PC and a backend process that runs on a remote PC. When the client needs to connect to the backend it first launches the remote process using WMI (code reproduced below). The remote process does a number of things including accessing a network share using Directory.GetDirectories() and reports back to the client.

When the remote process is launched automatically by the client using WMI, it cannot access the network share. However, if I connect to the remote machine using Remote Desktop and manually launch the backend process, access to the network share succeeds.

The user specifed in the WMI call and the user logged in for the Remote Desktop session are the same, so the permissions should be the same, shouldn't they?

I see in the MSDN entry for Directory.Exists() it states "The Exists method does not perform network authentication. If you query an existing network share without being pre-authenticated, the Exists method will return false." I assume this is related? How can I ensure the user is authenticated correctly in a WMI session?

ConnectionOptions opts = new ConnectionOptions();

opts.Username = username;
opts.Password = password;

ManagementPath path = new ManagementPath(string.Format("\\\\{0}\\root\\cimv2:Win32_Process", remoteHost));

ManagementScope scope = new ManagementScope(path, opts);

scope.Connect();

ObjectGetOptions getOpts = new ObjectGetOptions();
using (ManagementClass mngClass = new ManagementClass(scope, path, getOpts))
{
    ManagementBaseObject inParams = mngClass.GetMethodParameters("Create");
    inParams["CommandLine"] = commandLine;
    ManagementBaseObject outParams = mngClass.InvokeMethod("Create", inParams, null);
}

Answer 1

You can write all you commands to batch file to the remote machine which includes net use (no need to use a drive letter) to do an authentication. Works fine that way. I am still working on an alternative.

Answer 2

I know you've sorted it by using PSEXEC, which is a fantastic program, but if you did want to go back to WMI, have you tried enabling the following in your ConnectionOptions:

• The flag EnablePrivileges
• setting the Impersonation to ImpersonationLevel.Impersonate

Which does the following:

Gets or sets a value indicating whether user privileges need to be enabled for the connection operation. This property should only be used when the operation performed requires a certain user privilege to be enabled (for example, a machine restart).

http://msdn.microsoft.com/en-us/library/system.management.connectionoptions.enableprivileges.aspx

---

Gets or sets the COM impersonation level to be used for operations in this connection.

http://msdn.microsoft.com/en-us/library/system.management.connectionoptions.impersonation.aspx

I think they should tell your WMI to actually allow the program to have the correct credentials and thus access your network share

Answer 3

WMI just uses impersonation when executing the remote process, which does not give you network access. If you are ok going outside managed code, you can just map a UNC path in the remote process WMI started using whatever credentials you want. Then, you have the network access you want. I use NetUseAdd and NetUseDel from netapi32.dll to map the UNC path. See http://pinvoke.net/ for details on the using the APIs.

Answer 4

Having followed the link suggested by Isalamon above (thanks) I followed Jestro's advice and have rewritten using psexec.exe (which can be downloaded from http://technet.microsoft.com/en-us/sysinternals/bb897553.aspx) instead of WMI. It feels like a bit of a kludge to do it this way, but it seems to work.

New code for anyone who is experiencing similar problems:

Process proc = new Process();
proc.StartInfo.FileName = "PsExec.exe";
proc.StartInfo.Arguments = string.Format("\\\\{0} -d -u {1}\\{2} -p {3} {4}",
                                         remoteHost,
                                         domain,
                                         username,
                                         password,
                                         commandLine);
proc.StartInfo.CreateNoWindow = true;
proc.StartInfo.UseShellExecute = false;
proc.Start();