Click here to Skip to main content
15,867,308 members
Articles / Programming Languages / C++

Taking Advantage of the Winlogon Notification Package

Rate me:
Please Sign up or sign in to vote.
5.00/5 (18 votes)
6 Jan 2001CPOL 339.1K   78   105
Taking advantage of the Winlogon Notification Package
<!-- Add the rest of your HTML here -->

Introduction

The Winlogon Notification Package is a DLL which exports functions that handle Winlogon.exe events. These event messages includes lock, unlock, logoff, logon, startup, shutdown, startscreensaver, stopscreensaver, and startshell. 

This article demonstrates how to use the Winlogon Notification Package as an alternative to NT Services. The main benefits for doing this is better handling of user activities. In addition, the Winlogon Notification Package will be very lightweight and requires much less code then its NT service equivalent. 

The Steps

Creating a Winlogon Notification package is very simple. Just create a DLL with specific functions to run during the Winlogon event messages. To let Winlogon.exe know about your DLL, simply add a few entries into the registry where appropriate. This method can be quite robust and versatile when combined with your services and applications.

Sample

This sample starts a WIN32 application before the user logon. Because the process is started by Winlogon, it is owned by the system account. Users may not end the process through 'End Task'. This is the exact way NT services behave. In this sample, the logoff notification will terminate the process. If the process needed to stay active, the EndProcessAtWinlogoff function should be removed. If we wanted the process to be owned by the user, we could use CreateProcessAsUser during a startup notification instead of a logon notification. 

Step 1.) - the dll

//sample.cpp

#include <windows.h>
#include <Winwlx.h>

PROCESS_INFORMATION g_pi;
TCHAR g_szPath[] = _T("c:\somepath\execut.exe \"arguments\"");

//This function safely terminates a process, allowing
//it to do cleanup (ie. DLL detach)
//It can be found at the Windows Developer's Journal
SafeTerminateProcess(HANDLE hProcess, UINT uExitCode);   

//Entrance function for the DLL
BOOL WINAPI LibMain(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved)
{
    switch (dwReason)
    {
        case DLL_PROCESS_ATTACH:
        {
	    DisableThreadLibraryCalls (hInstance);	
        }
        break;
    }
    return TRUE;
}

//Event handler for the Winlogon Logon event
VOID APIENTRY StartProcessAtWinLogon (PWLX_NOTIFICATION_INFO pInfo)
{
    STARTUPINFO si;
    si.cb = sizeof(STARTUPINFO); 
    si.lpReserved = NULL; 
    si.lpTitle = NULL; 
    si.lpDesktop = "WinSta0\\Default"; 
    si.dwX = si.dwY = si.dwXSize = si.dwYSize = 0L; 
    si.dwFlags = 0;; 
    si.wShowWindow = SW_SHOW; 
    si.lpReserved2 = NULL; 
    si.cbReserved2 = 0; 
				
    CreateProcess(NULL, g_szPath, NULL, NULL, FALSE, CREATE_NEW_CONSOLE,
                  NULL, NULL, &si, &g_pi);
}

//Event handler for the Winlogon Logoff event.
VOID APIENTRY StopProcessAtWinLogoff (PWLX_NOTIFICATION_INFO pInfo)
{
    //terminates the process
    SafeTerminateProcess(g_pi.hProcess, 0xDEADBEEF);  
}

//other event handlers
VOID APIENTRY YOUR_EVENT_HANDLERS (PWLX_NOTIFICATION_INFO pInfo)
{
    //code
}

...

Step 2.) - the exports

The program hasn't exported any functions yet. We need to create a .def file.

sample.def

EXPORTS
StartProcessAtWinLogon
StopProcessAtWinLogoff

 

Now add the following to your linkage options in VC6 and build.

/def: "sample.def"

If everything went well, the files sample.dll and sample.exp will be in your output folder. Move these to \%NTROOT%\system32

Step 3.) - the registry

Add the following values and keys to the registry. These values communicate to Winlogon.exe and let it know which procedures to run during an event notification. Add as few or as many notification events as needed.

HKEY_LOCAL_MACHINE
    \Software
        \Microsoft
            \Windows NT
                \CurrentVersion
                    \Winlogon
                        \Notify
                            \NameOfProject
                                \Asynchronous  REG_DWORD  0
                                \Dllname       REG_SZ     NameOfDll.dll
                                \Impersonate   REG_DWORD  0
                                \Logon         REG_SZ     StartProcessAtWinLogon
                                \Logoff        REG_SZ     StopProcessAtWinLogoff
                                \...           REG_SZ     NameOfFunction

That's it! Now restart and Winlogon.exe will launch your app.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Architect Frontline Direct Inc., Adconion
United States United States
Tony Truong graduated from UCLA in Spring of 2001 and starting worked at Symantec Corporation as a Software Engineer. After a few years of developing various features for Norton SystemWorks, Tony moved to San Diego. He is currently writing database applications using ASP.NET and C# with the .NET Framework. Tony specializes in tara-byte databases with emphasis on high availability, optimization, and complex entity modeling.

Comments and Discussions

 
GeneralRe: change winlogon notification package timeout? Pin
chca26-Mar-05 2:32
chca26-Mar-05 2:32 
GeneralRe: change winlogon notification package timeout? Pin
Blake Miller28-Mar-05 4:13
Blake Miller28-Mar-05 4:13 
GeneralLoading a Dialog at Winlogon Startup Notification is Super Slow Pin
dbmabin1-Nov-04 10:42
dbmabin1-Nov-04 10:42 
GeneralRe: Loading a Dialog at Winlogon Startup Notification is Super Slow Pin
dbmabin9-Nov-04 11:04
dbmabin9-Nov-04 11:04 
GeneralRe: Loading a Dialog at Winlogon Startup Notification is Super Slow Pin
Blake Miller25-Mar-05 12:05
Blake Miller25-Mar-05 12:05 
General? Full documentation, Hibernate/Standby Pin
Synetech16-Oct-04 7:05
Synetech16-Oct-04 7:05 
GeneralRe: ? Full documentation, Hibernate/Standby Pin
Blake Miller25-Mar-05 12:02
Blake Miller25-Mar-05 12:02 
GeneralRe: ? Full documentation, Hibernate/Standby Pin
Coruscant6-Apr-05 12:38
Coruscant6-Apr-05 12:38 
GeneralRe: ? Full documentation, Hibernate/Standby Pin
Amit22038-Oct-07 3:19
Amit22038-Oct-07 3:19 
GeneralRe: ? Full documentation, Hibernate/Standby Pin
Michael Behan17-Apr-08 23:28
Michael Behan17-Apr-08 23:28 
Generalgina.dll implementing Pin
Tricksy23-May-04 16:11
Tricksy23-May-04 16:11 
GeneralPWLX_NOTIFICATION_INFO in C# Pin
Aisha Ikram22-Apr-04 20:47
Aisha Ikram22-Apr-04 20:47 
GeneralRe: PWLX_NOTIFICATION_INFO in C# Pin
mpeck27-Sep-04 9:25
mpeck27-Sep-04 9:25 
GeneralSomebody has some example Pin
Aitor Aiestaran21-Apr-04 1:06
Aitor Aiestaran21-Apr-04 1:06 
GeneralRe: Somebody has some example Pin
Blake Miller25-Mar-05 11:58
Blake Miller25-Mar-05 11:58 
Generalhave shell wait for process to finish Pin
Magic Steven1-Apr-04 1:41
sussMagic Steven1-Apr-04 1:41 
Generalcreating event dll in mfc shared dll Pin
Xins10-Mar-04 17:04
Xins10-Mar-04 17:04 
GeneralSame code in C# Pin
AgentM8-Mar-04 11:29
AgentM8-Mar-04 11:29 
GeneralRe: Same code in C# Pin
Tom Spink21-May-04 21:40
Tom Spink21-May-04 21:40 
GeneralAutomatic logon Pin
Andrew Groothedde25-Feb-04 4:26
sussAndrew Groothedde25-Feb-04 4:26 
GeneralRe: Automatic logon Pin
SohailB3-Sep-05 20:56
SohailB3-Sep-05 20:56 
Questioncan I use it on PDC to get logon info of entire network Pin
Member 4164053-Feb-04 20:06
Member 4164053-Feb-04 20:06 
GeneralWinlogon and AppBar Pin
jameyer7314-Jan-04 7:22
jameyer7314-Jan-04 7:22 
QuestionIs it true that the EXE loaded through this, will not give GUI??? Pin
Mr. Jigar Mehta6-Jan-04 2:16
Mr. Jigar Mehta6-Jan-04 2:16 
AnswerRe: Is it true that the EXE loaded through this, will not give GUI??? Pin
Mr. Jigar Mehta20-Feb-04 0:36
Mr. Jigar Mehta20-Feb-04 0:36 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.