diff --git a/base/setup/lib/setuplib.c b/base/setup/lib/setuplib.c
index 4e2b3fb4c39..e5ef76bbd44 100644
--- a/base/setup/lib/setuplib.c
+++ b/base/setup/lib/setuplib.c
@@ -235,6 +235,7 @@ InstallSetupInfFile(
     if (!IniCache)
         return;
 
+#if 0 /* If you need to put something in this section, do it after the merge with Unattend.inf */
     IniSection = IniAddSection(IniCache, L"SetupParams");
     if (IniSection)
     {
@@ -243,6 +244,7 @@ InstallSetupInfFile(
                             // L"\"%s\"", L"WinNt5.2");
         // IniAddKey(IniSection, L"Version", PathBuffer);
     }
+#endif
 
     IniSection = IniAddSection(IniCache, L"Data");
     if (IniSection)
diff --git a/boot/bootdata/bootcd/unattend.inf b/boot/bootdata/bootcd/unattend.inf
index 1ff70f9ddd5..c086ddfcf4e 100644
--- a/boot/bootdata/bootcd/unattend.inf
+++ b/boot/bootdata/bootcd/unattend.inf
@@ -59,6 +59,15 @@ LocaleID = 409
 ; 3 - ReactOS Nano Server (Reserved)
 InstallationType = 0
 
+;[GuiUnattended]
+; Run a program early in 2nd-stage setup.
+;DetachedProgram=%SystemRoot%\system32\cmd.exe
+;Arguments="/C echo.Early 2nd-stage setup...&choice>nul /N /T:Y,5"
+
+;[SetupParams]
+; Run a program at the end of 2nd-stage setup.
+;UserExecute="cmd.exe /C echo.End of 2nd-stage setup...&choice>nul /N /T:Y,5"
+
 ; Enable this section to automatically launch programs after 3rd boot.
 ;[GuiRunOnce]
 ;%SystemRoot%\system32\cmd.exe
diff --git a/dll/win32/syssetup/globals.h b/dll/win32/syssetup/globals.h
index c6c357222f8..f5bfa683ec3 100644
--- a/dll/win32/syssetup/globals.h
+++ b/dll/win32/syssetup/globals.h
@@ -73,6 +73,10 @@ HRESULT
 InstallOptionalComponents(
     _In_ PITEMSDATA pItemsData);
 
+HRESULT
+RunCommandAndWait(
+    _In_ PWCHAR Command);
+
 /* install */
 
 BOOL
@@ -109,6 +113,10 @@ VOID
 SetAutoAdminLogon(VOID);
 
 /* wizard.c */
-VOID InstallWizard (VOID);
+VOID
+InstallWizard(VOID);
+
+VOID
+GetSetupInfPath(PWSTR szPath, UINT cchMax);
 
 /* EOF */
diff --git a/dll/win32/syssetup/install.c b/dll/win32/syssetup/install.c
index 84906c6a8d6..9767fb3e68b 100644
--- a/dll/win32/syssetup/install.c
+++ b/dll/win32/syssetup/install.c
@@ -4,6 +4,7 @@
  * PURPOSE:           System setup
  * FILE:              dll/win32/syssetup/install.c
  * PROGRAMER:         Eric Kohl
+ *                    Whindmar Saksit <whindsaks@proton.me>
  */
 
 /* INCLUDES *****************************************************************/
@@ -985,6 +986,26 @@ cleanup:
     return bConsoleBoot;
 }
 
+static VOID
+ProcessDetachedProgram(
+    _In_ PCWSTR pszInf)
+{
+    WCHAR szInfApp[MAX_PATH], szInfArg[MAX_PATH * 3];
+    WCHAR szCmd[_countof(szInfApp) + _countof(szInfArg)];
+    UINT cch;
+
+    if (!GetPrivateProfileStringW(L"GuiUnattended", L"DetachedProgram", L"", szInfApp, _countof(szInfApp), pszInf) || !*szInfApp)
+        return;
+    cch = ExpandEnvironmentStrings(szInfApp, szCmd, _countof(szCmd) - 1);
+    if (GetPrivateProfileStringW(L"GuiUnattended", L"Arguments", L"", szInfArg, _countof(szInfArg), pszInf) && cch)
+    {
+        szCmd[cch - 1] = L' ';
+        szCmd[cch] = UNICODE_NULL;
+        ExpandEnvironmentStrings(szInfArg, szCmd + cch, _countof(szCmd) - cch);
+    }
+    RunCommandAndWait(szCmd);
+}
+
 extern VOID
 EnableVisualTheme(
     _In_opt_ HWND hwndParent,
@@ -1010,8 +1031,7 @@ PreprocessUnattend(
     {
         /* See also wizard.c!ProcessSetupInf()
          * Retrieve the path of the setup INF */
-        GetSystemDirectoryW(szPath, _countof(szPath));
-        wcscat(szPath, L"\\$winnt$.inf");
+        GetSetupInfPath(szPath, _countof(szPath));
     }
     else
     {
@@ -1038,6 +1058,9 @@ PreprocessUnattend(
 
     /* Enable the chosen theme, or use the classic theme */
     EnableVisualTheme(NULL, bDefaultThemesOff ? NULL : szValue);
+
+    if (IsInstall)
+        ProcessDetachedProgram(szPath);
 }
 
 static BOOL
diff --git a/dll/win32/syssetup/wizard.c b/dll/win32/syssetup/wizard.c
index d9d01da88a1..b0f4b646c6b 100644
--- a/dll/win32/syssetup/wizard.c
+++ b/dll/win32/syssetup/wizard.c
@@ -53,6 +53,13 @@ typedef struct _TIMEZONE_ENTRY
 
 extern void WINAPI Control_RunDLLW(HWND hWnd, HINSTANCE hInst, LPCWSTR cmd, DWORD nCmdShow);
 
+VOID
+GetSetupInfPath(PWSTR szPath, UINT cchMax)
+{
+    GetSystemDirectoryW(szPath, cchMax);
+    wcscat(szPath, L"\\$winnt$.inf");
+}
+
 static VOID
 CenterWindow(HWND hWnd)
 {
@@ -2740,31 +2747,38 @@ ProcessPageDlgProc(HWND hwndDlg,
 
 
 static VOID
-SetInstallationCompleted(VOID)
+SetInstallationCompleted(IN BOOL Unattended)
 {
     HKEY hKey = 0;
     DWORD InProgress = 0;
     DWORD InstallDate;
 
-    if (RegOpenKeyExW( HKEY_LOCAL_MACHINE,
-                       L"SYSTEM\\Setup",
-                       0,
-                       KEY_WRITE,
-                       &hKey ) == ERROR_SUCCESS)
-    {
-        RegSetValueExW( hKey, L"SystemSetupInProgress", 0, REG_DWORD, (LPBYTE)&InProgress, sizeof(InProgress) );
-        RegCloseKey( hKey );
-    }
-
-    if (RegOpenKeyExW( HKEY_LOCAL_MACHINE,
-                       L"Software\\Microsoft\\Windows NT\\CurrentVersion",
-                       0,
-                       KEY_WRITE,
-                       &hKey ) == ERROR_SUCCESS)
+    if (RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"Software\\Microsoft\\Windows NT\\CurrentVersion",
+                      0, KEY_WRITE, &hKey) == ERROR_SUCCESS)
     {
         InstallDate = (DWORD)time(NULL);
-        RegSetValueExW( hKey, L"InstallDate", 0, REG_DWORD, (LPBYTE)&InstallDate, sizeof(InstallDate) );
-        RegCloseKey( hKey );
+        RegSetValueExW(hKey, L"InstallDate", 0, REG_DWORD, (LPBYTE)&InstallDate, sizeof(InstallDate));
+        RegCloseKey(hKey);
+    }
+
+    if (Unattended)
+    {
+        WCHAR szInf[MAX_PATH];
+        WCHAR szInfCmd[MAX_PATH * 4], szCmd[_countof(szInfCmd)];
+
+        GetSetupInfPath(szInf, _countof(szInf));
+        if (GetPrivateProfileStringW(L"SetupParams", L"UserExecute", L"", szInfCmd, _countof(szInfCmd), szInf) && *szInfCmd)
+        {
+            *szCmd = UNICODE_NULL;
+            ExpandEnvironmentStringsW(szInfCmd, szCmd, _countof(szInfCmd));
+            RunCommandAndWait(szCmd);
+        }
+    }
+
+    if (RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SYSTEM\\Setup", 0, KEY_WRITE, &hKey) == ERROR_SUCCESS)
+    {
+        RegSetValueExW(hKey, L"SystemSetupInProgress", 0, REG_DWORD, (LPBYTE)&InProgress, sizeof(InProgress));
+        RegCloseKey(hKey);
     }
 }
 
@@ -2790,7 +2804,7 @@ FinishDlgProc(HWND hwndDlg,
             if (SetupData->UnattendSetup)
             {
                 KillTimer(hwndDlg, 1);
-                SetInstallationCompleted();
+                SetInstallationCompleted(TRUE);
                 PostQuitMessage(0);
             }
 
@@ -2802,7 +2816,7 @@ FinishDlgProc(HWND hwndDlg,
 
         case WM_DESTROY:
         {
-            SetInstallationCompleted();
+            SetInstallationCompleted(FALSE);
             PostQuitMessage(0);
             return TRUE;
         }
@@ -3335,8 +3349,7 @@ ProcessSetupInf(
     pSetupData->hSetupInf = INVALID_HANDLE_VALUE;
 
     /* Retrieve the path of the setup INF */
-    GetSystemDirectoryW(szPath, _countof(szPath));
-    wcscat(szPath, L"\\$winnt$.inf");
+    GetSetupInfPath(szPath, _countof(szPath));
 
     /* Open the setup INF */
     pSetupData->hSetupInf = SetupOpenInfFileW(szPath,