Run powershell command as currently logged in user - powershell

Question

Given a powershell script that runs as Local System (nt authority\system).
Is there a way to execute a command as the currently logged in user (without specifying the user password of course) ?
From what I've experimented so far is the Register-ScheduledTask cmdlet which takes an -User param. The task was scheduled and run successfully, but only works when the user is logged in.
Is there a better way to do it ?

Answer 1

I use schtasks.exe. I am not sure if this can be done in pure PS.
$user = Get-WmiObject -Class win32_computersystem | % Username
$computer = $env:COMPUTERNAME
$time = (Get-Date).AddMinutes(1).ToShortTimeString()
schtasks /create /s $computer /tn "RunCMD" /sc once /tr "cmd.exe" /st $time /ru $user

Answer 2

There is a complicated and round-about way of doing exactly this. It involves the API function CreateProcessAsUser. In order to call it, you need to obtain the TOKEN associated with the current console session, which can be done with the WTSQueryUserToken API function. This takes a session ID, which is obtained with the WTSGetActiveConsoleSessionId API function. (Many examples then show the token being duplicated, but from what I've read, this is unnecessary since WTSQueryUserToken already returns a primary token.)
You also need to initialize an environment block for the process you're going to create. For that, you use the CreateEnvironmentBlock API function. Make sure you specify the CREATE_UNICODE_ENVIRONMENT flag.
Of course, PowerShell cannot call these functions directly -- so you will have to dynamically compile some C# helper code and load it into the PowerShell environment.

Answer 3

Here is an article that has code to run notepad as the currently logged in user:
http://rzander.azurewebsites.net/create-a-process-as-loggedon-user/
Note: This solution looks like it requires the command be run from a system service due to how privileges are passed to child processes. Additionally the example does not work running from the system account because the working directory is not specified. Using the full path to the executable does work.
$Source = #"
using System;
using System.Runtime.InteropServices;
namespace murrayju.ProcessExtensions
{
public static class ProcessExtensions
{
#region Win32 Constants
private const int CREATE_UNICODE_ENVIRONMENT = 0x00000400;
private const int CREATE_NO_WINDOW = 0x08000000;
private const int CREATE_NEW_CONSOLE = 0x00000010;
private const uint INVALID_SESSION_ID = 0xFFFFFFFF;
private static readonly IntPtr WTS_CURRENT_SERVER_HANDLE = IntPtr.Zero;
#endregion
#region DllImports
[DllImport("advapi32.dll", EntryPoint = "CreateProcessAsUser", SetLastError = true, CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
private static extern bool CreateProcessAsUser(
IntPtr hToken,
String lpApplicationName,
String lpCommandLine,
IntPtr lpProcessAttributes,
IntPtr lpThreadAttributes,
bool bInheritHandle,
uint dwCreationFlags,
IntPtr lpEnvironment,
String lpCurrentDirectory,
ref STARTUPINFO lpStartupInfo,
out PROCESS_INFORMATION lpProcessInformation);
[DllImport("advapi32.dll", EntryPoint = "DuplicateTokenEx")]
private static extern bool DuplicateTokenEx(
IntPtr ExistingTokenHandle,
uint dwDesiredAccess,
IntPtr lpThreadAttributes,
int TokenType,
int ImpersonationLevel,
ref IntPtr DuplicateTokenHandle);
[DllImport("userenv.dll", SetLastError = true)]
private static extern bool CreateEnvironmentBlock(ref IntPtr lpEnvironment, IntPtr hToken, bool bInherit);
[DllImport("userenv.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool DestroyEnvironmentBlock(IntPtr lpEnvironment);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool CloseHandle(IntPtr hSnapshot);
[DllImport("kernel32.dll")]
private static extern uint WTSGetActiveConsoleSessionId();
[DllImport("Wtsapi32.dll")]
private static extern uint WTSQueryUserToken(uint SessionId, ref IntPtr phToken);
[DllImport("wtsapi32.dll", SetLastError = true)]
private static extern int WTSEnumerateSessions(
IntPtr hServer,
int Reserved,
int Version,
ref IntPtr ppSessionInfo,
ref int pCount);
#endregion
#region Win32 Structs
private enum SW
{
SW_HIDE = 0,
SW_SHOWNORMAL = 1,
SW_NORMAL = 1,
SW_SHOWMINIMIZED = 2,
SW_SHOWMAXIMIZED = 3,
SW_MAXIMIZE = 3,
SW_SHOWNOACTIVATE = 4,
SW_SHOW = 5,
SW_MINIMIZE = 6,
SW_SHOWMINNOACTIVE = 7,
SW_SHOWNA = 8,
SW_RESTORE = 9,
SW_SHOWDEFAULT = 10,
SW_MAX = 10
}
private enum WTS_CONNECTSTATE_CLASS
{
WTSActive,
WTSConnected,
WTSConnectQuery,
WTSShadow,
WTSDisconnected,
WTSIdle,
WTSListen,
WTSReset,
WTSDown,
WTSInit
}
[StructLayout(LayoutKind.Sequential)]
private struct PROCESS_INFORMATION
{
public IntPtr hProcess;
public IntPtr hThread;
public uint dwProcessId;
public uint dwThreadId;
}
private enum SECURITY_IMPERSONATION_LEVEL
{
SecurityAnonymous = 0,
SecurityIdentification = 1,
SecurityImpersonation = 2,
SecurityDelegation = 3,
}
[StructLayout(LayoutKind.Sequential)]
private struct STARTUPINFO
{
public int 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;
}
private enum TOKEN_TYPE
{
TokenPrimary = 1,
TokenImpersonation = 2
}
[StructLayout(LayoutKind.Sequential)]
private struct WTS_SESSION_INFO
{
public readonly UInt32 SessionID;
[MarshalAs(UnmanagedType.LPStr)]
public readonly String pWinStationName;
public readonly WTS_CONNECTSTATE_CLASS State;
}
#endregion
// Gets the user token from the currently active session
private static bool GetSessionUserToken(ref IntPtr phUserToken)
{
var bResult = false;
var hImpersonationToken = IntPtr.Zero;
var activeSessionId = INVALID_SESSION_ID;
var pSessionInfo = IntPtr.Zero;
var sessionCount = 0;
// Get a handle to the user access token for the current active session.
if (WTSEnumerateSessions(WTS_CURRENT_SERVER_HANDLE, 0, 1, ref pSessionInfo, ref sessionCount) != 0)
{
var arrayElementSize = Marshal.SizeOf(typeof(WTS_SESSION_INFO));
var current = pSessionInfo;
for (var i = 0; i < sessionCount; i++)
{
var si = (WTS_SESSION_INFO)Marshal.PtrToStructure((IntPtr)current, typeof(WTS_SESSION_INFO));
current += arrayElementSize;
if (si.State == WTS_CONNECTSTATE_CLASS.WTSActive)
{
activeSessionId = si.SessionID;
}
}
}
// If enumerating did not work, fall back to the old method
if (activeSessionId == INVALID_SESSION_ID)
{
activeSessionId = WTSGetActiveConsoleSessionId();
}
if (WTSQueryUserToken(activeSessionId, ref hImpersonationToken) != 0)
{
// Convert the impersonation token to a primary token
bResult = DuplicateTokenEx(hImpersonationToken, 0, IntPtr.Zero,
(int)SECURITY_IMPERSONATION_LEVEL.SecurityImpersonation, (int)TOKEN_TYPE.TokenPrimary,
ref phUserToken);
CloseHandle(hImpersonationToken);
}
return bResult;
}
public static bool StartProcessAsCurrentUser(string appPath, string cmdLine = null, string workDir = null, bool visible = true)
{
var hUserToken = IntPtr.Zero;
var startInfo = new STARTUPINFO();
var procInfo = new PROCESS_INFORMATION();
var pEnv = IntPtr.Zero;
int iResultOfCreateProcessAsUser;
startInfo.cb = Marshal.SizeOf(typeof(STARTUPINFO));
try
{
if (!GetSessionUserToken(ref hUserToken))
{
throw new Exception("StartProcessAsCurrentUser: GetSessionUserToken failed.");
}
uint dwCreationFlags = CREATE_UNICODE_ENVIRONMENT | (uint)(visible ? CREATE_NEW_CONSOLE : CREATE_NO_WINDOW);
startInfo.wShowWindow = (short)(visible ? SW.SW_SHOW : SW.SW_HIDE);
startInfo.lpDesktop = "winsta0\\default";
if (!CreateEnvironmentBlock(ref pEnv, hUserToken, false))
{
throw new Exception("StartProcessAsCurrentUser: CreateEnvironmentBlock failed.");
}
if (!CreateProcessAsUser(hUserToken,
appPath, // Application Name
cmdLine, // Command Line
IntPtr.Zero,
IntPtr.Zero,
false,
dwCreationFlags,
pEnv,
workDir, // Working directory
ref startInfo,
out procInfo))
{
throw new Exception("StartProcessAsCurrentUser: CreateProcessAsUser failed.\n");
}
iResultOfCreateProcessAsUser = Marshal.GetLastWin32Error();
}
finally
{
CloseHandle(hUserToken);
if (pEnv != IntPtr.Zero)
{
DestroyEnvironmentBlock(pEnv);
}
CloseHandle(procInfo.hThread);
CloseHandle(procInfo.hProcess);
}
return true;
}
}
}
"#
Add-Type -ReferencedAssemblies 'System', 'System.Runtime.InteropServices' -TypeDefinition $Source -Language CSharp
[murrayju.ProcessExtensions.ProcessExtensions]::StartProcessAsCurrentUser('c:\\windows\\system32\\notepad.exe')

Answer 4

You can use the portable powershell app deployment kit (Link). You can edit the deploy-application.ps1 with your code and run it elevated use/add Execute-ProcessAsUser in the script to run applications/scripts with the current user without a prompt for credentials.