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Taking Advantage of the Winlogon Notification Package

, 6 Jan 2001
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Taking advantage of the Winlogon Notification Package
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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 has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Tony Truong
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

 
QuestionWill not work on Vista and later. PinmemberAssaf Levy4-Oct-11 5:17 
AnswerRe: Will not work on Vista and later. Pinmemberisabelprgmr29-Aug-12 12:23 
QuestionHow to start service... Pinmembergothic_coder27-May-10 3:54 
QuestionMinGW c/c++ attempt ...I'm stuck, any ideas? Pinmembertwohawks2-Mar-10 16:52 
AnswerRe: MinGW c/c++ attempt ...I'm stuck, any ideas? Pinmembertwohawks2-Mar-10 17:55 
AnswerRe: MinGW c/c++ attempt ...some progress... Pinmembertwohawks2-Mar-10 19:07 
QuestionCan I see the notpad's and logon's UI at same time? PinmemberAson18-Feb-09 21:14 
GeneralError:unresolved external symbol "int __cdecl SafeTerminateProcess(void *,unsigned int)" PinmemberRajeshshewale6-Jun-08 19:32 
GeneralWinLogon Notification Package PinmemberBodanapu14-Sep-07 0:45 
AnswerRe: WinLogon Notification Package PinmemberA56471828-Sep-07 7:22 
GeneralRe: WinLogon Notification Package PinmemberMember 857955622-Feb-12 0:06 
GeneralCan't make this thing to work Pinmembersdrey19-Jul-07 18:54 
GeneralNotification Packages removed on vista Pinmemberppckiller4-Jun-07 7:27 
Questionhow to create and use manifest file in winlogon package Pinmemberprem kumar singh22-Dec-06 1:47 
QuestionHow to bypass the logon windows( user to input username and password) PinmemberJohngle29-Oct-06 17:07 
QuestionComplete Sample for Novice PinmemberVindalf27-Aug-06 9:18 
GeneralWinlogon notification packages in Non-Domain env.! Pinmemberbaluspage17-Aug-06 20:30 
QuestionHow to get this code to work with VS.NET 2003? Pinmemberid10t24-May-06 2:44 
QuestionEvent DLL not working on clean install of XP ? Pinmembermojomonkeyhelper25-Sep-05 23:36 
AnswerRe: Event DLL not working on clean install of XP ? Pinmembermojomonkeyhelper26-Sep-05 23:00 
GeneralDebug version works, release version doesn't PinsussAaron Reeves3-May-05 11:29 
GeneralWorks on XP, does not work on 2003 Server PinmemberAlpar26-Apr-05 10:15 
QuestionNo more information than in MSDN, surely? PinmemberCoruscant6-Apr-05 12:41 
Questionchange winlogon notification package timeout? Pinmemberchca6-Jan-05 9:48 
AnswerRe: change winlogon notification package timeout? PinmemberBlake Miller25-Mar-05 12:07 
GeneralRe: change winlogon notification package timeout? Pinmemberchca26-Mar-05 2:32 
GeneralRe: change winlogon notification package timeout? PinmemberBlake Miller28-Mar-05 4:13 
GeneralLoading a Dialog at Winlogon Startup Notification is Super Slow Pinmemberdbmabin1-Nov-04 10:42 
GeneralRe: Loading a Dialog at Winlogon Startup Notification is Super Slow Pinmemberdbmabin9-Nov-04 11:04 
GeneralRe: Loading a Dialog at Winlogon Startup Notification is Super Slow PinmemberBlake Miller25-Mar-05 12:05 
General? Full documentation, Hibernate/Standby PinmemberSynetech16-Oct-04 7:05 
GeneralRe: ? Full documentation, Hibernate/Standby PinmemberBlake Miller25-Mar-05 12:02 
GeneralRe: ? Full documentation, Hibernate/Standby PinmemberCoruscant6-Apr-05 12:38 
GeneralRe: ? Full documentation, Hibernate/Standby PinmemberAmit22038-Oct-07 3:19 
GeneralRe: ? Full documentation, Hibernate/Standby PinmemberMichael Behan17-Apr-08 23:28 
Generalgina.dll implementing PinmemberTricksy23-May-04 16:11 
GeneralPWLX_NOTIFICATION_INFO in C# PinmemberAisha Ikram22-Apr-04 20:47 
GeneralRe: PWLX_NOTIFICATION_INFO in C# PinsussMike Peck27-Sep-04 9:25 
GeneralSomebody has some example PinmemberAitor Aiestaran21-Apr-04 1:06 
GeneralRe: Somebody has some example PinmemberBlake Miller25-Mar-05 11:58 
Generalhave shell wait for process to finish PinsussMagic Steven1-Apr-04 1:41 
Generalcreating event dll in mfc shared dll PinmemberXins10-Mar-04 17:04 
GeneralSame code in C# PinmemberAgentM8-Mar-04 11:29 
GeneralRe: Same code in C# PinmemberTom Spink21-May-04 21:40 
GeneralAutomatic logon PinsussAndrew Groothedde25-Feb-04 4:26 
GeneralRe: Automatic logon PinmemberSohailB3-Sep-05 20:56 
Questioncan I use it on PDC to get logon info of entire network Pinmembervijayv3-Feb-04 20:06 
GeneralWinlogon and AppBar Pinmemberjameyer7314-Jan-04 7:22 
QuestionIs it true that the EXE loaded through this, will not give GUI??? PinmemberMr. Jigar Mehta6-Jan-04 2:16 
AnswerRe: Is it true that the EXE loaded through this, will not give GUI??? PinmemberMr. Jigar Mehta20-Feb-04 0:36 

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