Getting logged-on username from a service

Question

I have a service that I had to log on to the local admin to install. The pupose of this service to log when a user is logging in or out to record their username. I finally found a bit of WMI code that I thought would work, but it is still returning Administrator. Why isn't this working?

var query = new ObjectQuery("SELECT * FROM Win32_Process WHERE Name = 'explorer.exe'");
var explorerProcesses = new ManagementObjectSearcher(query).Get();

foreach (ManagementObject mo in explorerProcesses)
{
    string[] ownerInfo = new string[2];
    mo.InvokeMethod("GetOwner", (object[])ownerInfo);

    userName = String.Concat(ownerInfo[1], @"\", ownerInfo[0]);
}
Console.WriteLine(userName);
Console.ReadLine();

To clarify my question I'm tring to get the currently logged on user but its giving me back Adminstrator the account I used to install the service.

Answer 1

You should use Service Control Manager Notifications for this. You can configure your service to receive notification events when a user logs on and / or logs off. This allows a service to do interactive user impersonation if the service requires it, but it should give you the info you need for your logging.

Check out the section "Using Service Control Manager (SCM) Notifications" here http://technet.microsoft.com/en-us/library/cc721961(WS.10).aspx

edit

In your Service class override the OnSessionChange event handler to check for logon and logoff events.

protected override void OnSessionChange(SessionChangeDescription changeDescription)
{
    base.OnSessionChange(changeDescription);

    switch (changeDescription.Reason)
    {
        case SessionChangeReason.SessionLogon:
            // do your logging here
            break;

        case SessionChangeReason.SessionLogoff:
            // do your logging here
            break;
    }
}

edit2:

class Class1
{
    [DllImport("Advapi32.dll")]
    static extern bool GetUserName(StringBuilder lpBuffer, ref int nSize);    
    [STAThread]
    static void Main(string[] args)
    {
        StringBuilder Buffer = new StringBuilder(64);
        int nSize=64;
        GetUserName(Buffer, ref nSize);
        Console.WriteLine(Buffer.ToString());
    }
}

edit3:

public class InteractiveUser
{
    [DllImport("wtsapi32.dll", SetLastError = true)]
    static extern bool WTSQueryUserToken(UInt32 sessionId, out IntPtr Token);

    [DllImport("kernel32.dll")]
    private static extern UInt32 WTSGetActiveConsoleSessionId();

    enum TOKEN_INFORMATION_CLASS
    {
        TokenUser = 1,
        TokenGroups,
        TokenPrivileges,
        TokenOwner,
        TokenPrimaryGroup,
        TokenDefaultDacl,
        TokenSource,
        TokenType,
        TokenImpersonationLevel,
        TokenStatistics,
        TokenRestrictedSids,
        TokenSessionId,
        TokenGroupsAndPrivileges,
        TokenSessionReference,
        TokenSandBoxInert,
        TokenAuditPolicy,
        TokenOrigin
    }

    public struct TOKEN_USER 
    { 
        public SID_AND_ATTRIBUTES User; 
    } 

    [StructLayout(LayoutKind.Sequential)]
    public struct SID_AND_ATTRIBUTES 
    { 
        public IntPtr Sid; 
        public int Attributes; 
    } 

    // Using IntPtr for pSID insted of Byte[]
    [DllImport("advapi32", CharSet=CharSet.Auto, SetLastError=true)]
    static extern bool ConvertSidToStringSid(
        IntPtr pSID, 
        out IntPtr ptrSid);

    [DllImport("kernel32.dll")]
    static extern IntPtr LocalFree(IntPtr hMem);

    [DllImport("advapi32.dll", SetLastError=true)]
    static extern bool GetTokenInformation(
        IntPtr TokenHandle,
        TOKEN_INFORMATION_CLASS TokenInformationClass,
        IntPtr TokenInformation,
        int TokenInformationLength,
        out int ReturnLength);

    private static string GetSID(IntPtr token)
    {
        bool Result;

        int TokenInfLength = 0; 
        string sidAsString = String.Empty;

        // first call gets lenght of TokenInformation
        Result = GetTokenInformation( token , TOKEN_INFORMATION_CLASS.TokenUser , IntPtr.Zero , TokenInfLength , out TokenInfLength ); 

        IntPtr TokenInformation = Marshal.AllocHGlobal( TokenInfLength ) ; 
        Result = GetTokenInformation( token  , TOKEN_INFORMATION_CLASS.TokenUser , TokenInformation , TokenInfLength , out TokenInfLength ) ; 

        if ( Result ) 
        {
            TOKEN_USER TokenUser = ( TOKEN_USER )Marshal.PtrToStructure( TokenInformation , typeof( TOKEN_USER ) ) ; 

            IntPtr pstr = IntPtr.Zero; 
            Boolean ok = ConvertSidToStringSid( TokenUser.User.Sid  , out pstr ); 

            sidAsString = Marshal.PtrToStringAuto( pstr ); 
            LocalFree(pstr);
        }

        Marshal.FreeHGlobal( TokenInformation );

        return sidAsString;
    }

    public static string Account()
    {
        IntPtr token = IntPtr.Zero;
        String account = String.Empty;

        if (WTSQueryUserToken(WTSGetActiveConsoleSessionId(), out token))
        {
            String sid = GetSID(token);
            account =
                new SecurityIdentifier(sid).Translate(typeof(NTAccount)).ToString();
        }
        else
        {
            int err = Marshal.GetLastWin32Error();
            switch (err)
            {
                case 5:
                    account = "ERROR_ACCESS_DENIED";
                    break;
                case 87:
                    account = "ERROR_INVALID_PARAMETER";
                    break;
                case 1008:
                    account = "ERROR_NO_TOKEN";
                    break;
                case 1314:
                    account = "ERROR_PRIVILEGE_NOT_HELD";
                    break;
                case 7022:
                    account = "ERROR_CTX_WINSTATION_NOT_FOUND";
                    break;
                default:
                    account = String.Format("ERROR_{0}", err.ToString());
                    break;
            }
        }

        return account;
    }
}

Answer 2

I know this thread is old, but if anyone need to know how it works:

Add a reference to System.Management

Put using System.Management; at the top of your file

Create this private variable in your class:

private readonly ManagementClass _wmiComputerSystem = new ManagementClass("Win32_ComputerSystem");

Create this method in your service:

protected override void OnSessionChange(SessionChangeDescription changeDescription)
{
   base.OnSessionChange(changeDescription);

   switch (changeDescription.Reason)
   {
      case SessionChangeReason.SessionLogon:
      {
         string user = "";

         foreach (ManagementObject currentObject in _wmiComputerSystem.GetInstances())
         {
            user = currentObject.Properties["UserName"].Value.ToString().Trim();
         }
      } break;
   }
}

Now you got the username in user. If the computer is in a domain it looks like this domain\username

Answer 3

Try to change the Account() method inserting the sessionId parameter and passing the changeDescription.SessionId to the method WTSQueryUserToken

public static string Account(uint sessionId)
{
     IntPtr token = IntPtr.Zero;
     String account = String.Empty;
     if (WTSQueryUserToken(sessionId, out token))
     { 
     ...
     ...

p.s.: Run your service with LocalSystem account

Answer 4

Here's my code (all of them residing inside a class; in my case, the class inheriting ServiceBase).

    [DllImport("Wtsapi32.dll")]
    private static extern bool WTSQuerySessionInformation(IntPtr hServer, int sessionId, WtsInfoClass wtsInfoClass, out IntPtr ppBuffer, out int pBytesReturned);
    [DllImport("Wtsapi32.dll")]
    private static extern void WTSFreeMemory(IntPtr pointer);

    private enum WtsInfoClass
    {
        WTSUserName = 5, 
        WTSDomainName = 7,
    }

    private static string GetUsername(int sessionId, bool prependDomain = true)
    {
        IntPtr buffer;
        int strLen;
        string username = "SYSTEM";
        if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WtsInfoClass.WTSUserName, out buffer, out strLen) && strLen > 1)
        {
            username = Marshal.PtrToStringAnsi(buffer);
            WTSFreeMemory(buffer);
            if (prependDomain)
            {
                if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WtsInfoClass.WTSDomainName, out buffer, out strLen) && strLen > 1)
                {
                    username = Marshal.PtrToStringAnsi(buffer) + "\\" + username;
                    WTSFreeMemory(buffer);
                }
            }
        }
        return username;
    }

With the above code in your class, you can simply get the username in the method you're overriding like this:

protected override void OnSessionChange(SessionChangeDescription changeDescription)
{
    string username = GetUsername(changeDescription.SessionId);
    //continue with any other thing you wish to do
}