#!/usr/bin/env python3 """ WinMsg Tester v1.0.0 wireandbrain.com — free tools from the bench Test whether text and keystrokes can be injected into any Windows application window. Useful for diagnosing UI automation issues and understanding Windows User Interface Privilege Isolation (UIPI) security boundaries. Three injection methods tested, top to bottom: A. SendInput — OS-level injection, most reliable for modern apps B. PostMessage WM_CHAR — classic Win32, works on most native controls C. WM_SETTEXT — sets edit control text directly Requirements: Python 3.9+, Windows only (uses ctypes + win32 APIs) No external libraries needed. Usage: python winmsg_tester.py License: MIT — free to use, modify, and distribute. """ import tkinter as tk from tkinter import ttk, scrolledtext import ctypes import ctypes.wintypes import time U32 = ctypes.windll.user32 # Win32 message constants WM_CHAR = 0x0102 WM_KEYDOWN = 0x0100 WM_KEYUP = 0x0101 WM_SETTEXT = 0x000C VK_RETURN = 0x0D VK_LBUTTON = 0x01 # SendInput structures INPUT_KEYBOARD = 1 KEYEVENTF_UNICODE = 0x0004 KEYEVENTF_KEYUP = 0x0002 class KEYBDINPUT(ctypes.Structure): _fields_ = [ ("wVk", ctypes.wintypes.WORD), ("wScan", ctypes.wintypes.WORD), ("dwFlags", ctypes.wintypes.DWORD), ("time", ctypes.wintypes.DWORD), ("dwExtraInfo", ctypes.POINTER(ctypes.c_ulong)), ] class _INPUT_UNION(ctypes.Union): _fields_ = [("ki", KEYBDINPUT)] class INPUT(ctypes.Structure): _fields_ = [("type", ctypes.wintypes.DWORD), ("_input", _INPUT_UNION)] def _send_input_text(text: str, send_enter: bool = False) -> int: """ Inject text using SendInput — operates below the Win32 message queue. Most reliable method for Electron, WPF, and other framework-hosted apps. Returns number of input events successfully injected. Note: Will be blocked by UIPI if target process runs at higher integrity level (e.g., apps running as Administrator when this tool is not). """ inputs = [] for ch in text: scan = ord(ch) for flags in (KEYEVENTF_UNICODE, KEYEVENTF_UNICODE | KEYEVENTF_KEYUP): ki = KEYBDINPUT(wVk=0, wScan=scan, dwFlags=flags, time=0, dwExtraInfo=None) inputs.append(INPUT(type=INPUT_KEYBOARD, _input=_INPUT_UNION(ki=ki))) if send_enter: for flags in (0, KEYEVENTF_KEYUP): ki = KEYBDINPUT(wVk=VK_RETURN, wScan=0, dwFlags=flags, time=0, dwExtraInfo=None) inputs.append(INPUT(type=INPUT_KEYBOARD, _input=_INPUT_UNION(ki=ki))) arr = (INPUT * len(inputs))(*inputs) return U32.SendInput(len(inputs), arr, ctypes.sizeof(INPUT)) def _get_window_title(hwnd: int) -> str: buf = ctypes.create_unicode_buffer(256) U32.GetWindowTextW(hwnd, buf, 256) return buf.value def _hwnd_at_cursor() -> tuple: pt = ctypes.wintypes.POINT() U32.GetCursorPos(ctypes.byref(pt)) hwnd = U32.WindowFromPoint(pt) return hwnd, _get_window_title(hwnd) class WinMsgTester(tk.Tk): def __init__(self): super().__init__() self.title("WinMsg Tester v1.0.0 — wireandbrain.com") self.resizable(False, False) self.attributes("-topmost", True) self.target_hwnd = None self._picking = False self._btn_was_up = True self._build_ui() self._poll_cursor() def _build_ui(self): PAD = dict(padx=8, pady=4) # ── UIPI notice ───────────────────────────────────────────────────── note = ttk.Label( self, text=( "ℹ UIPI note: Electron, Chrome, and elevated-privilege apps block" " all three methods by design. That is expected — not a bug." ), foreground="#888", wraplength=640, justify="left" ) note.grid(row=0, column=0, columnspan=2, sticky="w", padx=10, pady=(6, 0)) # ── Pick target ───────────────────────────────────────────────────── frm = ttk.LabelFrame(self, text="1. Pick Target Window") frm.grid(row=1, column=0, columnspan=2, sticky="ew", **PAD) ttk.Label(frm, text="HWND:").grid(row=0, column=0, sticky="w") self.hwnd_var = tk.StringVar(value="(none)") self.title_var = tk.StringVar(value="") ttk.Label(frm, textvariable=self.hwnd_var, width=12, relief="sunken") \ .grid(row=0, column=1, sticky="w", padx=4) ttk.Label(frm, textvariable=self.title_var, width=42, relief="sunken") \ .grid(row=0, column=2, sticky="w", padx=4) self.pick_btn = ttk.Button(frm, text="⊕ Pick Window", command=self._start_pick) self.pick_btn.grid(row=0, column=3, padx=8) self.hover_var = tk.StringVar( value="Click 'Pick Window', hover over any app window, then left-click to capture.") ttk.Label(frm, textvariable=self.hover_var, foreground="gray", width=74) \ .grid(row=1, column=0, columnspan=4, sticky="w", pady=(0, 4)) # ── Message ───────────────────────────────────────────────────────── frm2 = ttk.LabelFrame(self, text="2. Message") frm2.grid(row=2, column=0, columnspan=2, sticky="ew", **PAD) self.msg_var = tk.StringVar(value="Hello from WinMsg Tester") ttk.Label(frm2, text="Text:").grid(row=0, column=0, sticky="w") ttk.Entry(frm2, textvariable=self.msg_var, width=50) \ .grid(row=0, column=1, padx=6, pady=4) self.enter_var = tk.BooleanVar(value=True) ttk.Checkbutton(frm2, text="Append Enter", variable=self.enter_var) \ .grid(row=0, column=2, padx=4) # ── Send methods ──────────────────────────────────────────────────── frm3 = ttk.LabelFrame( self, text="3. Send Method (try A first — fall back to B or C if needed)") frm3.grid(row=3, column=0, columnspan=2, sticky="ew", **PAD) btns = [ ("A: SendInput (OS-level, best for modern apps)", self._do_send_input, "Injects below Win32 queue. Brings window to foreground first."), ("B: PostMessage WM_CHAR", self._do_wm_char, "Classic Win32. Works on most native Edit controls. Text only — Enter via WM_KEYDOWN."), ("C: WM_SETTEXT (replaces field contents)", self._do_settext, "Sets text of target control directly. No keystroke simulation."), ] for i, (label, cmd, hint) in enumerate(btns): ttk.Button(frm3, text=label, command=cmd) \ .grid(row=i, column=0, padx=6, pady=4, sticky="w") ttk.Label(frm3, text=hint, foreground="gray") \ .grid(row=i, column=1, sticky="w", padx=4) # ── Log ───────────────────────────────────────────────────────────── frm4 = ttk.LabelFrame(self, text="Result Log") frm4.grid(row=4, column=0, columnspan=2, sticky="ew", **PAD) self.log = scrolledtext.ScrolledText( frm4, height=10, width=80, state="disabled", font=("Consolas", 9)) self.log.grid(row=0, column=0, padx=4, pady=4) ttk.Button(frm4, text="Clear", command=self._clear_log) \ .grid(row=1, column=0, sticky="e", padx=4, pady=(0, 4)) # ── Footer ────────────────────────────────────────────────────────── ttk.Label(self, text="wireandbrain.com | v1.0.0 | MIT License", foreground="#777", font=("", 8)) \ .grid(row=5, column=0, columnspan=2, pady=(2, 6)) # ── CURSOR POLL ───────────────────────────────────────────────────────── def _poll_cursor(self): if self._picking: hwnd, title = _hwnd_at_cursor() self.hover_var.set( f"Under cursor → {hex(hwnd)} " f"[{(title or '(no title)')[:55]}] LEFT-CLICK to capture") btn_down = bool(U32.GetAsyncKeyState(VK_LBUTTON) & 0x8000) if self._btn_was_up and btn_down and hwnd != self.winfo_id(): self._capture(hwnd, title) self._picking = False self._btn_was_up = True self.pick_btn.config(state="normal") self._btn_was_up = not btn_down self.after(80, self._poll_cursor) def _start_pick(self): self._picking = True self._btn_was_up = False self.pick_btn.config(state="disabled") self.hover_var.set("Move cursor to target window and LEFT-CLICK to capture...") def _capture(self, hwnd: int, title: str): self.target_hwnd = hwnd self.hwnd_var.set(hex(hwnd)) self.title_var.set((title or "(no title)")[:50]) self._log(f"[PICK] HWND {hex(hwnd)} — {(title or '(no title)')[:70]}") # ── SEND METHODS ──────────────────────────────────────────────────────── def _get_target(self): if not self.target_hwnd: self._log("[ERROR] No target window selected. Click 'Pick Window' first.") return None return self.target_hwnd def _do_send_input(self): hwnd = self._get_target() if hwnd is None: return msg, enter = self.msg_var.get(), self.enter_var.get() try: U32.SetForegroundWindow(hwnd) self.after(200, lambda: self._send_input_deferred(hwnd, msg, enter)) except Exception as e: self._log(f"[SendInput] SetForegroundWindow error: {e}") def _send_input_deferred(self, hwnd, msg, enter): try: sent = _send_input_text(msg, send_enter=enter) suffix = " + Enter" if enter else "" self._log( f"[A: SendInput] → {hex(hwnd)} | " f"'{msg}'{suffix} | {sent} events injected") except Exception as e: self._log(f"[A: SendInput] ERROR: {e}") def _do_wm_char(self): hwnd = self._get_target() if hwnd is None: return msg, enter = self.msg_var.get(), self.enter_var.get() try: for ch in msg: U32.PostMessageW(hwnd, WM_CHAR, ord(ch), 1) if enter: U32.PostMessageW(hwnd, WM_KEYDOWN, VK_RETURN, 1) U32.PostMessageW(hwnd, WM_KEYUP, VK_RETURN, 1) suffix = " + Enter" if enter else "" self._log( f"[B: WM_CHAR] → {hex(hwnd)} | " f"'{msg}'{suffix} | posted") except Exception as e: self._log(f"[B: WM_CHAR] ERROR: {e}") def _do_settext(self): hwnd = self._get_target() if hwnd is None: return msg = self.msg_var.get() try: result = U32.SendMessageW(hwnd, WM_SETTEXT, 0, msg) self._log( f"[C: WM_SETTEXT] → {hex(hwnd)} | " f"'{msg}' | result={result}") except Exception as e: self._log(f"[C: WM_SETTEXT] ERROR: {e}") # ── LOG ───────────────────────────────────────────────────────────────── def _log(self, msg: str): ts = time.strftime("%H:%M:%S") self.log.config(state="normal") self.log.insert("end", f"[{ts}] {msg}\n") self.log.see("end") self.log.config(state="disabled") def _clear_log(self): self.log.config(state="normal") self.log.delete("1.0", "end") self.log.config(state="disabled") if __name__ == "__main__": app = WinMsgTester() app.mainloop()