Windows Startup Methods

Posted on July 1, 2009. Filed under: Computer, Tutorials, Windows/7 | Tags: , , , |

     Need to find out where programs launch themselves from? Check out the following..

      Run – These are the most common startup locations for programs. In HKEY_LOCAL_MACHINE, the file will startup for all users. In HKEY_CURRENT_USER, it will startup only with the current user. By default these keys are not executed in Safe mode. If you prefix the value of these keys with an asterisk, *, it will run in Safe Mode.

Registry Keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\ CurrentVersion\Run

HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\Run

      RunOnce Local Machine Key – These keys are designed to be used primarily by Setup programs. Entries in these keys are started once and then are deleted from the key. If there a exclamation point preceding the value of the key, the entry will not be deleted until after the program completes, otherwise it will be deleted before the program runs. This is important, because if the exclamation point is not used, and the program referenced in this key fails to complete, it will not run again as it will have already been deleted. All entries in this key are started synchronously in an undefined order. Due to this, all programs in this key must be finished before any entries in HKEY_LOCAL_MACHINE\…\Run, HKEY_CURRENT_USER\…\Run, HKEY_CURRENT_USER\…\RunOnce, and Startup Folders can be loaded. The RunOnce keys are ignored under Windows 2000 and Windows XP in Safe Mode. The RunOnce keys are not supported by Windows NT 3.51.

Registry Keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\ CurrentVersion\RunOnce

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\ CurrentVersion\RunOnceEx



RunOnce Current User Key

Registry Key:

HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\RunOnce

      RunServicesOnce – This key is designed to start services when a computer boots up (only on next startup). These entries can also continue running even after you log on, but must be completed before the HKEY_LOCAL_MACHINE\…\RunOnce registry can start loading its programs.

Registry Keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\ CurrentVersion\RunServicesOnce 

HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\RunServicesOnce

      RunServices – This key is designed to start services as well. These entries can also continue running even after you log on, but must be completed before the HKEY_LOCAL_MACHINE\…\RunOnce registry can start loading its programs.

Registry Keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\ CurrentVersion\RunServices 

HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\RunServices

Logon Prompt is placed on Screen. After a user logs in the rest of the keys continue.

    ActiveX Component – This is the startup method used by Bifrost
Registry keys:

HKEY_CURRENT_USER\Software\Microsoft\Active Setup\Installed Components\{4175C5F3-D47F-143B-DD4D-E67A0EB4E773} – StubPath = "Exe path"

HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components\{4175C5F3-D47F-143B-DD4D-E67A0EB4E773} – StubPath = "Exe path"

       All Users Startup Folder – For Windows XP, 2000, and NT, this folder is used for programs that should be auto started for all users who will login to this computer. It is generally found at:

Windows XP C:\Documents and Settings\All Users\Start Menu\Programs\Startup

Windows NT C:\wont\Profiles\All Users\Start Menu\Programs\Startup

Windows 2000 C:\Documents and Settings\All Users\Start Menu\Programs\Startup

      User Profile Startup Folder – This folder will be executed for the particular user who logs in. This folder is usually found in:

Win 9X, ME C:\windows\start menu\programs\startup

Windows XP C:\Documents and Settings\LoginName\Start Menu\Programs\Startup

     Explorer Run – These keys is generally used to load programs as part of a policy set in place on the computer or user. Pain RAT server can use this key to run on startup

Registry Keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\ CurrentVersion\Policies\Explorer\Run

HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\Policies\Explorer\Run

     UserInit Key – This key specifies what program should be launched right after a user logs into Windows. The default program for this key is C:\windows\system32\userinit.exe. Userinit.exe is a program that restores your profile, fonts, colors, etc for your username. It is possible to add further programs that will launch from this key by separating the programs with a comma.

For example:

  HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit =C:\windows\system32\userinit.exe, c:\windows\badprogram.exe.

     This will make both programs launch when you log in and is a common place for trojans, hijackers, and spyware to launch from.

Registry Key:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit

     Load Key – This key is not commonly used anymore, but can be used to auto start programs.

Registry Key:

HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows\load

      Notify – This key is used to add a program that will run when a particular event occurs. Events include logon, logoff, startup, shutdown, startscreensaver, and stopscreensaver. When Winlogon.exe generates an event such as the ones listed, Windows will look in the Notify registry key for a DLL that will handle this event. Malware has been known to use this method to load itself when a user logs on to their computer. Loading in such a way allows the malware program to load in such a way that it is not easy to stop.

Registry Key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify

      AppInit_DLLs – This value corresponds to files being loaded through the AppInit_DLLs Registry value.
The AppInit_DLLs registry value contains a list of dlls that will be loaded when user32.dll is loaded. As most Windows executables use the user32.dll, that means that any DLL that is listed in the AppInit_DLLs registry key will be loaded also. This makes it very difficult to remove the DLL as it will be loaded within multiple processes, some of which can not be stopped without causing system instability. The user32.dll file is also used by processes that are automatically started by the system when you log on. This means that the files loaded in the AppInit_DLLs value will be loaded very early in the Windows startup routine allowing the DLL to hide itself or protect itself before we have access to the system.

Registry Key:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Windows

      ShellServiceObjectDelayLoad – This Registry contains values in a similar way as the Run key does. The difference is that instead of pointing to the file itself, it points to the CLSID’s InProcServer, which contains the information about the particular DLL file that is being used.

The files under this key are loaded automatically by Explorer.exe when your computer starts. Because Explorer.exe is the shell for your computer, it will always start, thus always loading the files under this key. These files are therefore loaded early in the startup process before any human intervention occurs.

Registry Key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\ CurrentVersion\ShellServiceObjectDelayLoad

     SharedTaskScheduler – This section corresponds to files being loaded through the SharedTaskScheduler registry value for XP, NT, 2000 machines..
The entries in this registry run automatically when you start windows.

Registry Key:

 HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\ CurrentVersion\Explorer\SharedTaskScheduler

The following are files that programs can autostart from on bootup:

1. c:\autoexec.bat

2. c:\config.sys

3. windir\wininit.ini – Usually used by setup programs to have a file run once and then get deleted.

4. windir\winstart.bat

5. windir\win.ini – [windows] "load"

6. windir\win.ini – [windows] "run"

7. windir\system.ini – [boot] "shell"

8. windir\system.ini – [boot] "scrnsave.exe"

9. windir\dosstart.bat – Used in Win95 or 98 when you select the "Restart in MS-DOS mode" in the shutdown menu.

10. windir\system\autoexec.nt

11. windir\system\config.nt




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