Run program as different user on Windows (not admin) within a Python script

Question

With the following code:

class ImpersonateWin32Sec(object):

    def __init__(self, domain, username, password):
        self.username = username
        self.password = password
        self.domain = domain
        self.handle = None

    def __enter__(self):
        self.handle = win32security.LogonUser(self.username, self.domain, self.password, win32con.LOGON32_LOGON_INTERACTIVE, win32con.LOGON32_PROVIDER_DEFAULT)
        win32security.ImpersonateLoggedOnUser(self.handle)

    def __exit__(self, *args):
        win32security.RevertToSelf()
        self.handle.Close()

with ImpersonateWin32Sec("domain", "altuser", "password"):
    prc = subprocess.Popen(cmdLine, cwd = "C:\\Temp", stdin = subprocess.PIPE, stdout = subprocess.PIPE, stderr = subprocess.PIPE, env = env, shell = shell, creationflags = CREATE_NO_WINDOW)
    stdOut, stdErr = prc.communicate(timeout = 60)

I'm trying to run a program as a different user. It seems to work only partially, because some commands fail. The following 3 commands show that some parts of the environment are still for the original user:

os.getlogin() # altuser
getpass.getuser() # origuser   --> WRONG!!!
win32api.GetUserName() # altuser

What is missing/wrong with my code? I've found some information that ImpersonateLoggedOnUser creates an impersonate token for the user, instead of a primary token? Could this be the problem? If yes how can I get a primary token? A code example would be very appreciated.

Regards, Martin

Answer 1

Finally I've found out how to do this. It is rather complicated and I had to merge the code from several examples (some of them in C). The below example works when executed as Network Service or System user. It doesn't matter if executed in user session or session 0.

Here is the code:

import os
import msvcrt
import win32security
import win32con
import win32pipe
import win32process
import win32api
import win32net
import win32file
import win32event
import win32profile
import win32service


GENERIC_ACCESS = win32con.GENERIC_READ | win32con.GENERIC_WRITE | win32con.GENERIC_EXECUTE | win32con.GENERIC_ALL

WINSTA_ALL = (win32con.WINSTA_ACCESSCLIPBOARD  | win32con.WINSTA_ACCESSGLOBALATOMS | \
win32con.WINSTA_CREATEDESKTOP    | win32con.WINSTA_ENUMDESKTOPS      | \
win32con.WINSTA_ENUMERATE        | win32con.WINSTA_EXITWINDOWS       | \
win32con.WINSTA_READATTRIBUTES   | win32con.WINSTA_READSCREEN        | \
win32con.WINSTA_WRITEATTRIBUTES  | win32con.DELETE                   | \
win32con.READ_CONTROL            | win32con.WRITE_DAC                | \
win32con.WRITE_OWNER)

DESKTOP_ALL = (win32con.DESKTOP_CREATEMENU      | win32con.DESKTOP_CREATEWINDOW  | \
win32con.DESKTOP_ENUMERATE       | win32con.DESKTOP_HOOKCONTROL   | \
win32con.DESKTOP_JOURNALPLAYBACK | win32con.DESKTOP_JOURNALRECORD | \
win32con.DESKTOP_READOBJECTS     | win32con.DESKTOP_SWITCHDESKTOP | \
win32con.DESKTOP_WRITEOBJECTS    | win32con.DELETE                | \
win32con.READ_CONTROL            | win32con.WRITE_DAC             | \
win32con.WRITE_OWNER)


def runAsDomainUser(domainName, userName, password, cmdLine, maxWait):
    # maxWait = Maximum execution time in ms
    userGroupSid = win32security.LookupAccountName(domainName, userName)[0]
    # Login as domain user and create new session
    userToken = win32security.LogonUser(userName, domainName, password,
                                        win32con.LOGON32_LOGON_INTERACTIVE,
                                        win32con.LOGON32_PROVIDER_DEFAULT)
    rc = win32api.GetLastError()
    if userToken is None or (rc != 0):
        return -1, "", "LogonUser failed with RC=%d!" % rc
    profileDir = win32profile.GetUserProfileDirectory(userToken)
    tokenUser = win32security.GetTokenInformation(userToken, win32security.TokenUser)

    # Set access rights to window station
    hWinSta = win32service.OpenWindowStation("winsta0", False, win32con.READ_CONTROL | win32con.WRITE_DAC )
    # Get security descriptor by winsta0-handle
    secDescWinSta = win32security.GetUserObjectSecurity(hWinSta, win32security.OWNER_SECURITY_INFORMATION
                                                                 | win32security.DACL_SECURITY_INFORMATION
                                                                 | win32con.GROUP_SECURITY_INFORMATION)
    # Get DACL from security descriptor
    daclWinSta = secDescWinSta.GetSecurityDescriptorDacl()
    if daclWinSta is None:
        # Create DACL if not exisiting
        daclWinSta = win32security.ACL()
    # Add ACEs to DACL for specific user group
    daclWinSta.AddAccessAllowedAce(win32security.ACL_REVISION_DS, GENERIC_ACCESS, userGroupSid)
    daclWinSta.AddAccessAllowedAce(win32security.ACL_REVISION_DS, WINSTA_ALL, userGroupSid)
    # Set modified DACL for winsta0
    win32security.SetSecurityInfo(hWinSta, win32security.SE_WINDOW_OBJECT, win32security.DACL_SECURITY_INFORMATION,
                                  None, None, daclWinSta, None)

    # Set access rights to desktop
    hDesktop = win32service.OpenDesktop("default", 0, False, win32con.READ_CONTROL
                                                             | win32con.WRITE_DAC
                                                             | win32con.DESKTOP_WRITEOBJECTS
                                                             | win32con.DESKTOP_READOBJECTS)
    # Get security descriptor by desktop-handle
    secDescDesktop = win32security.GetUserObjectSecurity(hDesktop, win32security.OWNER_SECURITY_INFORMATION
                                                                   | win32security.DACL_SECURITY_INFORMATION
                                                                   | win32con.GROUP_SECURITY_INFORMATION )
    # Get DACL from security descriptor
    daclDesktop = secDescDesktop.GetSecurityDescriptorDacl()
    if daclDesktop is None:
        #create DACL if not exisiting
        daclDesktop = win32security.ACL()
    # Add ACEs to DACL for specific user group
    daclDesktop.AddAccessAllowedAce(win32security.ACL_REVISION_DS, GENERIC_ACCESS, userGroupSid)
    daclDesktop.AddAccessAllowedAce(win32security.ACL_REVISION_DS, DESKTOP_ALL, userGroupSid)
    # Set modified DACL for desktop
    win32security.SetSecurityInfo(hDesktop, win32security.SE_WINDOW_OBJECT, win32security.DACL_SECURITY_INFORMATION,
                                  None, None, daclDesktop, None)

    # Setup stdin, stdOut and stderr
    secAttrs = win32security.SECURITY_ATTRIBUTES()
    secAttrs.bInheritHandle = 1
    stdOutRd, stdOutWr = win32pipe.CreatePipe(secAttrs, 0)
    stdErrRd, stdErrWr = win32pipe.CreatePipe(secAttrs, 0)

    ppid = win32api.GetCurrentProcess()
    tmp = win32api.DuplicateHandle(ppid, stdOutRd, ppid, 0, 0, win32con.DUPLICATE_SAME_ACCESS)
    win32file.CloseHandle(stdOutRd)
    stdOutRd = tmp

    environment = win32profile.CreateEnvironmentBlock(userToken, False)

    startupInfo = win32process.STARTUPINFO()
    startupInfo.dwFlags = win32con.STARTF_USESTDHANDLES
    startupInfo.hStdOutput = stdOutWr
    startupInfo.hStdError = stdErrWr

    hPrc = win32process.CreateProcessAsUser(
                            userToken,
                            None,               # appName
                            cmdLine,            # commandLine
                            None,               # processAttributes
                            None,               # threadAttributes
                            1,                  # bInheritHandles
                            win32process.CREATE_NEW_CONSOLE, # dwCreationFlags
                            environment,        # newEnvironment
                            profileDir,         # currentDirectory
                            startupInfo)[0]

    win32file.CloseHandle(stdErrWr)
    win32file.CloseHandle(stdOutWr)
    win32security.RevertToSelf()

    # Wait for process to complete
    stdOutBuf = os.fdopen(msvcrt.open_osfhandle(stdOutRd, 0), "rb")
    stdErrBuf = os.fdopen(msvcrt.open_osfhandle(stdErrRd, 0), "rb")
    win32event.WaitForSingleObject(hPrc, maxWait)
    stdOut = stdOutBuf.read()
    stdErr = stdErrBuf.read()
    rc = win32process.GetExitCodeProcess(hPrc)
    return rc, str(stdOut, "utf-8"), str(stdErr, "utf-8")


if __name__ == "__main__":
    cmdLine = "C:/Windows/System32/cmd.exe"
    domainName = input("Domain: ")
    userName = input("User: ")
    password = input("Password: ")
    print(runAsDomainUser(domainName, userName, password, cmdLine, 60000))