Added DLL code to prevent full-screen screenshots of processes in the sandbox.

Sandboxie/core/dll/gui.c

@@ -380,6 +380,9 @@ _FX BOOLEAN Gui_Init(HMODULE module)
     Gui_UseProxyService = !Dll_CompartmentMode && !SbieApi_QueryConfBool(NULL, L"NoSandboxieDesktop", FALSE);
     // NoSbieDesk END
 
+	GUI_IMPORT___(GetWindowDC)
+	GUI_IMPORT___(GetDC)
+	GUI_IMPORT___(GetDCEx)
     GUI_IMPORT___(GetWindowThreadProcessId);
     GUI_IMPORT___(SetThreadDesktop);
     GUI_IMPORT___(SwitchDesktop);

Sandboxie/core/dll/gui_p.h

@@ -412,6 +412,12 @@ typedef int (*P_LoadString)(
 
 typedef BOOL (*P_SetProcessWindowStation)(HWINSTA hWinSta);
 
+typedef BOOL(*P_GetWindowDC)(HWND hWnd);
+
+typedef BOOL(*P_GetDC)(HWND hWnd);
+
+typedef BOOL(*P_GetDCEx)(HWND hWnd,HRGN hrgnClip,DWORD flags);
+
 typedef BOOL (*P_SetThreadDesktop)(HDESK hDesktop);
 
 typedef BOOL (*P_SwitchDesktop)(HDESK hDesktop);
@@ -534,6 +540,9 @@ extern ATOM Gui_WindowProcOldA_Atom;
 #endif
 #define GUI_SYS_VAR_2(nm)       GUI_SYS_VAR_AW(nm,A); GUI_SYS_VAR_AW(nm,W);
 
+GUI_SYS_VAR(GetDC)
+GUI_SYS_VAR(GetDCEx)
+GUI_SYS_VAR(GetWindowDC)
 
 GUI_SYS_VAR(ClipCursor)
 GUI_SYS_VAR(GetClipCursor)

Sandboxie/core/dll/guimisc.c

@@ -176,7 +176,9 @@ _FX BOOLEAN Gui_InitMisc(HMODULE module)
         }
         SBIEDLL_HOOK_GUI(SwapMouseButton);
         SBIEDLL_HOOK_GUI(SetDoubleClickTime);
-
+		SBIEDLL_HOOK_GUI(GetWindowDC)
+		SBIEDLL_HOOK_GUI(GetDC)
+		SBIEDLL_HOOK_GUI(GetDCEx)
         if (Dll_OsBuild >= 6000) {
 
             //
@@ -1458,3 +1460,56 @@ _FX BOOL Gui_ImmAssociateContextEx(
 
     return ok;
 }
+
+//---------------------------------------------------------------------------
+// Gui_GetDC
+//---------------------------------------------------------------------------
+
+
+_FX HDC Gui_GetDC(HWND hWnd)
+{
+	if (SbieApi_QueryConfBool(NULL, L"IsBlockCapture", FALSE)) {
+		if (hWnd == NULL || hWnd == GetDesktopWindow()) {
+			SetLastError(ERROR_ACCESS_DENIED);
+			return NULL;
+		}
+		ULONG_PTR pid, tid;
+		if (!Gui_IsSameBox(hWnd, pid, tid)) {
+			SetLastError(ERROR_ACCESS_DENIED);
+			return NULL;
+		}
+	}
+	return __sys_GetDC(hWnd);
+}
+
+_FX HDC Gui_GetWindowDC(HWND hWnd)
+{
+	if (SbieApi_QueryConfBool(NULL, L"IsBlockCapture", FALSE)) {
+		if (hWnd == NULL || hWnd == GetDesktopWindow()) {
+			SetLastError(ERROR_ACCESS_DENIED);
+			return NULL;
+		}
+		ULONG_PTR pid, tid;
+		if (!Gui_IsSameBox(hWnd, pid, tid)) {
+			SetLastError(ERROR_ACCESS_DENIED);
+			return NULL;
+		}
+	}
+	return __sys_GetWindowDC(hWnd);
+}
+
+_FX HDC Gui_GetDCEx(HWND hWnd,HRGN  hrgnClip,DWORD flags)
+{
+	if (SbieApi_QueryConfBool(NULL, L"IsBlockCapture", FALSE)) {
+		if (hWnd == NULL || hWnd == GetDesktopWindow()) {
+			SetLastError(ERROR_ACCESS_DENIED);
+			return NULL;
+		}
+		ULONG_PTR pid, tid;
+		if (!Gui_IsSameBox(hWnd, pid, tid)) {
+			SetLastError(ERROR_ACCESS_DENIED);
+			return NULL;
+		}
+	}
+	return __sys_GetWindowDC(hWnd);
+}