Registry Run Keys / Startup Folder

Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. Adding an entry to the "run keys" in the Registry or startup folder will cause the program referenced to be executed when a user logs in. These programs will be executed under the context of the user and will have the account's associated permissions level.

Placing a program within a startup folder will also cause the program to execute when a user logs in. There is a startup folder location for individual user accounts as well as a system-wide startup folder that will be checked regardless of which user account logs in. The startup folder path for the current user is: C:\Users[Username]\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup. The startup folder path for all users is: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp.

The following run keys are created by default on Windows systems:

· HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

· HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce

· HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

· HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce

Run keys may exist under multiple hives. The

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnceEx is also available but is not created by default on Windows Vista and newer. Registry run key entries can reference programs directly or list them as a dependency. For example, it is possible to load a DLL at logon using a "Depend" key with RunOnceEx: reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnceEx\0001\Depend /v 1 /d "C:\temp\evil[.]dll"

The following Registry keys can control automatic startup of services during boot:

· HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServicesOnce

· HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServicesOnce

· HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices

· HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServices

Using policy settings to specify startup programs creates corresponding values in either of two Registry keys:

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

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

The Winlogon key controls actions that occur when a user logs on to a computer running Windows 7. Most of these actions are under the control of the operating system, but you can also add custom actions here. The

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

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell subkeys can automatically launch programs.

Programs listed in the load value of the registry key

HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows run when any user logs on.

Be default, the multistring BootExecute value of the registry key

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager is set to autocheck autochk *. This value causes Windows, at startup, to check the file-system integrity of the hard disks if the system has been shut down abnormally. Adversaries can add other programs or processes to this registry value which will automatically launch at boot.

Adversaries can use these configuration locations to execute malware, such as remote access tools, to maintain persistence through system reboots. Adversaries may also use Masquerading to make the Registry entries look as if they are associated with legitimate programs.

StartUp Folder:

The startup folder as the name implies a folder containing programs that will initiate at Boot Time once a user has logged onto their session, we can apply this method to a single User or to All Users depending on the level of permissions we currently hold, in the following example I will just setup a simple BAT file on the startup folder for my current user and login back to the machine and have that file get executed once the user has logged on to the workstation.

Bat File

I placed a simple bat script on the startup menu so when the user logs back in this will get executed.

Demo:

Registry Run Keys:

From here we will also create a new Registry Key at User Level Permission and have it execute our code.

This code will get Execute every time a user logs in after every reboot or shutdown. We can see how it works in the following Demo.

Demo: