Question

I found this tutorial on how getting Idle time of the user Idle Time.

The problem is that it will only work if the application runs on the user.

And my application runs on SYSTEM.

How can I get the idle time? or if PC is idle?

Answer 1

As I understood, you are okay with the result of GetLastInputInfo function. Thus I would suggest the following.

Now, suppose you have executable A that runs under Local System account. Create executable B that will gather relevant system information (with the help of GetLastInputInfo). Next, run executable B from executable A using this class which uses CreateProcessAsUser function with the logged user token (unfortunately I was unable to find stackoverflow question in which it was published):

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace Helpers
{
    [StructLayout(LayoutKind.Sequential)]
    internal struct PROCESS_INFORMATION
    {
        public IntPtr hProcess;
        public IntPtr hThread;
        public uint dwProcessId;
        public uint dwThreadId;
    }

    [StructLayout(LayoutKind.Sequential)]
    internal struct SECURITY_ATTRIBUTES
    {
        public uint nLength;
        public IntPtr lpSecurityDescriptor;
        public bool bInheritHandle;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct STARTUPINFO
    {
        public uint cb;
        public string lpReserved;
        public string lpDesktop;
        public string lpTitle;
        public uint dwX;
        public uint dwY;
        public uint dwXSize;
        public uint dwYSize;
        public uint dwXCountChars;
        public uint dwYCountChars;
        public uint dwFillAttribute;
        public uint dwFlags;
        public short wShowWindow;
        public short cbReserved2;
        public IntPtr lpReserved2;
        public IntPtr hStdInput;
        public IntPtr hStdOutput;
        public IntPtr hStdError;
    }

    internal enum SECURITY_IMPERSONATION_LEVEL
    {
        SecurityAnonymous,
        SecurityIdentification,
        SecurityImpersonation,
        SecurityDelegation
    }

    internal enum TOKEN_TYPE
    {
        TokenPrimary = 1,
        TokenImpersonation
    }

    public class ImpersonateProcessAsLoggedUser
    {
        private const short SW_SHOW = 5;
        private const uint TOKEN_QUERY = 0x0008;
        private const uint TOKEN_DUPLICATE = 0x0002;
        private const uint TOKEN_ASSIGN_PRIMARY = 0x0001;
        private const int GENERIC_ALL_ACCESS = 0x10000000;
        private const int STARTF_USESHOWWINDOW = 0x00000001;
        private const int STARTF_FORCEONFEEDBACK = 0x00000040;
        private const uint CREATE_UNICODE_ENVIRONMENT = 0x00000400;

        [DllImport("advapi32.dll", SetLastError = true)]
        private static extern bool CreateProcessAsUser(
            IntPtr hToken,
            string lpApplicationName,
            string lpCommandLine,
            ref SECURITY_ATTRIBUTES lpProcessAttributes,
            ref SECURITY_ATTRIBUTES lpThreadAttributes,
            bool bInheritHandles,
            uint dwCreationFlags,
            IntPtr lpEnvironment,
            string lpCurrentDirectory,
            ref STARTUPINFO lpStartupInfo,
            out PROCESS_INFORMATION lpProcessInformation);


        [DllImport("advapi32.dll", EntryPoint = "DuplicateTokenEx", SetLastError = true)]
        private static extern bool DuplicateTokenEx(
            IntPtr hExistingToken,
            uint dwDesiredAccess,
            ref SECURITY_ATTRIBUTES lpThreadAttributes,
            Int32 ImpersonationLevel,
            Int32 dwTokenType,
            ref IntPtr phNewToken);


        [DllImport("advapi32.dll", SetLastError = true)]
        private static extern bool OpenProcessToken(
            IntPtr ProcessHandle,
            UInt32 DesiredAccess,
            ref IntPtr TokenHandle);

        [DllImport("userenv.dll", SetLastError = true)]
        private static extern bool CreateEnvironmentBlock(
            ref IntPtr lpEnvironment,
            IntPtr hToken,
            bool bInherit);


        [DllImport("userenv.dll", SetLastError = true)]
        private static extern bool DestroyEnvironmentBlock(
            IntPtr lpEnvironment);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern bool CloseHandle(
            IntPtr hObject);


        private static bool LaunchProcessAsUser(string cmdLine, IntPtr token, IntPtr envBlock)
        {
            bool result = false;


            var pi = new PROCESS_INFORMATION();
            var saProcess = new SECURITY_ATTRIBUTES();
            var saThread = new SECURITY_ATTRIBUTES();
            saProcess.nLength = (uint) Marshal.SizeOf(saProcess);
            saThread.nLength = (uint) Marshal.SizeOf(saThread);

            var si = new STARTUPINFO();
            si.cb = (uint) Marshal.SizeOf(si);


            //if this member is NULL, the new process inherits the desktop
            //and window station of its parent process. If this member is
            //an empty string, the process does not inherit the desktop and
            //window station of its parent process; instead, the system
            //determines if a new desktop and window station need to be created.
            //If the impersonated user already has a desktop, the system uses the
            //existing desktop.

            si.lpDesktop = @"WinSta0\Default"; //Modify as needed
            si.dwFlags = STARTF_USESHOWWINDOW | STARTF_FORCEONFEEDBACK;
            si.wShowWindow = SW_SHOW;
            //Set other si properties as required.

            result = CreateProcessAsUser(
                token,
                null,
                cmdLine,
                ref saProcess,
                ref saThread,
                false,
                CREATE_UNICODE_ENVIRONMENT,
                envBlock,
                null,
                ref si,
                out pi);


            if (result == false)
            {
                int error = Marshal.GetLastWin32Error();
                string message = String.Format("CreateProcessAsUser Error: {0}", error);
                Debug.WriteLine(message);
            }

            return result;
        }


        private static IntPtr GetPrimaryToken(int processId)
        {
            IntPtr token = IntPtr.Zero;
            IntPtr primaryToken = IntPtr.Zero;
            bool retVal = false;
            Process p = null;

            try
            {
                p = Process.GetProcessById(processId);
            }

            catch (ArgumentException)
            {
                string details = String.Format("ProcessID {0} Not Available", processId);
                Debug.WriteLine(details);
                throw;
            }


            //Gets impersonation token
            retVal = OpenProcessToken(p.Handle, TOKEN_DUPLICATE, ref token);
            if (retVal)
            {
                var sa = new SECURITY_ATTRIBUTES();
                sa.nLength = (uint) Marshal.SizeOf(sa);

                //Convert the impersonation token into Primary token
                retVal = DuplicateTokenEx(
                    token,
                    TOKEN_ASSIGN_PRIMARY | TOKEN_DUPLICATE | TOKEN_QUERY,
                    ref sa,
                    (int) SECURITY_IMPERSONATION_LEVEL.SecurityIdentification,
                    (int) TOKEN_TYPE.TokenPrimary,
                    ref primaryToken);

                //Close the Token that was previously opened.
                CloseHandle(token);
                if (retVal == false)
                {
                    string message = String.Format("DuplicateTokenEx Error: {0}", Marshal.GetLastWin32Error());
                    Debug.WriteLine(message);
                }
            }

            else
            {
                string message = String.Format("OpenProcessToken Error: {0}", Marshal.GetLastWin32Error());
                Debug.WriteLine(message);
            }

            //We'll Close this token after it is used.
            return primaryToken;
        }

        private static IntPtr GetEnvironmentBlock(IntPtr token)
        {
            IntPtr envBlock = IntPtr.Zero;
            bool retVal = CreateEnvironmentBlock(ref envBlock, token, false);
            if (retVal == false)
            {
                //Environment Block, things like common paths to My Documents etc.
                //Will not be created if "false"
                //It should not adversley affect CreateProcessAsUser.

                string message = String.Format("CreateEnvironmentBlock Error: {0}", Marshal.GetLastWin32Error());
                Debug.WriteLine(message);
            }
            return envBlock;
        }

        public static bool Launch(string appCmdLine /*,int processId*/)
        {
            bool ret = false;

            //Either specify the processID explicitly
            //Or try to get it from a process owned by the user.
            //In this case assuming there is only one explorer.exe

            Process[] ps = Process.GetProcessesByName("explorer");
            int processId = -1; //=processId
            if (ps.Length > 0)
            {
                processId = ps[0].Id;
            }

            if (processId > 1)
            {
                IntPtr token = GetPrimaryToken(processId);

                if (token != IntPtr.Zero)
                {
                    IntPtr envBlock = GetEnvironmentBlock(token);
                    ret = LaunchProcessAsUser(appCmdLine, token, envBlock);
                    if (envBlock != IntPtr.Zero)
                        DestroyEnvironmentBlock(envBlock);

                    CloseHandle(token);
                }
            }
            return ret;
        }
    }
}

Next, you need to find a way for sending gathered information from executable B to executable A. There are numerous methods to do this. One of those is .Net Remoting. However you can go with creating an intermediate XML or even text file.

Maybe it is not the best way to solve your problem, but if you will need more Local System <-> Logged User interactions, you have a pattern to follow.