Run / RunOnce (Elevated)

You can use the following registry entries to specify applications to run at logon:

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce
HKLM\Software\Microsoft\Windows\CurrentVersion\Run
HKLM\Software\Microsoft\Windows\CurrentVersion\RunOnce

Let's then create a REG_EXPAND_SZ registry entry under

HKLM\Software\Microsoft\Windows\CurrentVersion\Run

After doing this, sign out of your current session and log in again, and you should receive a shell.