C# Signature:

[DllImport("advapi32.dll", SetLastError=true)]
static extern TODO ImpersonateLoggedOnUser(TODO);

VB Signature:

Declare Function ImpersonateLoggedOnUser Lib "advapi32.dll" (ByVal hToken As Integer) As Integer

User-Defined Types:

None.

Notes:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/secauthz/security/impersonateloggedonuser.asp

Tips & Tricks:

Don't forget to call RevertToSelf when done.

Sample Code:

Public Sub Logon(ByVal strUser As String, ByVal strPassword As String, ByVal strDomain As String)

    Dim lngLogonType, lngLogonProvider, lngTokenHandle As Integer
    Dim blnResult As Boolean

    lngLogonType = LOGON32_LOGON_INTERACTIVE
    lngLogonProvider = LOGON32_PROVIDER_DEFAULT

    blnResult = RevertToSelf()

    blnResult = LogonUser(strUser, strDomain, strPassword, _
                         lngLogonType, lngLogonProvider, _
                         lngTokenHandle)
    If blnResult Then
        blnResult = ImpersonateLoggedOnUser(lngTokenHandle)
        CloseHandle(lngTokenHandle)
    Else
        MsgBox("Error logging on")
    End If

End Sub

Alternative Managed API:

Do you know one? Please contribute it!