Can't Impersonate on Windows Service - c#-4.0

Question

I am using Impersonation in my program. I don't have any problem. However, when I create Windows Service, I am having an exception while impersonating. What can be the problem? In my account, I can successfully apply impersonation but windows services run on Local System account. Is it a problem?
Here is my code:
public enum SECURITY_IMPERSONATION_LEVEL : int
{
SecurityAnonymous = 0,
SecurityIdentification = 1,
SecurityImpersonation = 2,
SecurityDelegation = 3
}
public static WindowsImpersonationContext ImpersonateUser(string sUsername, string sDomain, string sPassword)
{
// initialize tokens
IntPtr pExistingTokenHandle = new IntPtr(0);
IntPtr pDuplicateTokenHandle = new IntPtr(0);
pExistingTokenHandle = IntPtr.Zero;
pDuplicateTokenHandle = IntPtr.Zero;
// if domain name was blank, assume local machine
if (sDomain == "")
sDomain = System.Environment.MachineName;
try
{
string sResult = null;
const int LOGON32_PROVIDER_DEFAULT = 0;
const int LOGON32_LOGON_INTERACTIVE = 2;
// get handle to token
bool bImpersonated = LogonUser(sUsername, sDomain, sPassword,
LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref pExistingTokenHandle);
// did impersonation fail?
if (!bImpersonated)
{
//Giriş yapılırken hata ile karşılaşıldı
Helper.ShowErrorMsg(ErrorAndInfoMessages.ErrorOnLogon);
return null;
}
// Get identity before impersonation
sResult += "Before impersonation: " + WindowsIdentity.GetCurrent().Name + "\r\n";
bool bRetVal = DuplicateToken(pExistingTokenHandle, (int)SECURITY_IMPERSONATION_LEVEL.SecurityImpersonation, ref pDuplicateTokenHandle);
// did DuplicateToken fail?
if (!bRetVal)
{
//DuplicateToken() failed
Helper.ShowErrorMsg(ErrorAndInfoMessages.ErrorTokenFailed);
return null;
}
else
{
// create new identity using new primary token
WindowsIdentity newId = new WindowsIdentity(pDuplicateTokenHandle);
WindowsImpersonationContext impersonatedUser = newId.Impersonate();
// check the identity after impersonation
sResult += "After impersonation: " + WindowsIdentity.GetCurrent().Name + "\r\n";
return impersonatedUser;
}
}
catch (Exception ex)
{
Helper.ShowErrorMsg("ImpersonateUser Hata: " + ex.Message);
return null;
}
finally
{
// close handle(s)
if (pExistingTokenHandle != IntPtr.Zero)
CloseHandle(pExistingTokenHandle);
if (pDuplicateTokenHandle != IntPtr.Zero)
CloseHandle(pDuplicateTokenHandle);
}
}
Here is the exception:
Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation. Specify the ServiceNotification or DefaultDesktopOnly style to display a notification from a service application.
I also tried run windows service with my account but nothing had changed.

Answer 1

Try using LOGON32_LOGON_NETWORK = 3 instead of LOGON32_LOGON_INTERACTIVE = 2.
According to MSDN LOGON32_LOGON_INTERACTIVE is intended for users who will be interactively using the computer, therefore an unattended process like a windows service could fail.
We ran into the same issue and the above change fixed it.