Implemented input injection checking in hooks

Author: Visual-Vincent

InputHelper/AssemblyInfo.vb

@@ -5,5 +5,5 @@ Imports System.Resources
 <Assembly: AssemblyDescription("A .NET friendly library for simulating mouse and keyboard input.")>
 <Assembly: AssemblyProduct("InputHelper")>
 <Assembly: AssemblyCopyright("Copyright © Vincent Bengtsson 2016-2022")>
-<Assembly: AssemblyVersion("2.0.0.0")>
+<Assembly: AssemblyVersion("2.1.0.0")>
 <Assembly: NeutralResourcesLanguage("en")>

InputHelper/EventArgs/KeyboardHookEventArgs.vb

@@ -45,6 +45,8 @@ Namespace EventArgs
         Inherits System.EventArgs
 
         Private _extended As Boolean
+        Private _injected As Boolean
+        Private _injectedAtLowerIL As Boolean
         Private _keyCode As Keys
         Private _keyState As KeyState
         Private _modifiers As ModifierKeys
@@ -67,6 +69,26 @@ Namespace EventArgs
             End Get
         End Property
 
+        ''' <summary>
+        ''' Gets a boolean value indicating whether the keystroke was injected into the input stream by a process rather than an input device.
+        ''' </summary>
+        ''' <remarks>Always False for <see cref="LocalKeyboardHook"/>.</remarks>
+        Public ReadOnly Property Injected As Boolean
+            Get
+                Return _injected
+            End Get
+        End Property
+
+        ''' <summary>
+        ''' Gets a boolean value indicating whether the keystroke was injected into the input stream by another process running at lower integrity level.
+        ''' </summary>
+        ''' <remarks>Always False for <see cref="LocalKeyboardHook"/>.</remarks>
+        Public ReadOnly Property InjectedAtLowerIL As Boolean
+            Get
+                Return _injectedAtLowerIL
+            End Get
+        End Property
+
         ''' <summary>
         ''' Gets the keyboard code of the key that generated the keystroke.
         ''' </summary>
@@ -108,8 +130,8 @@ Namespace EventArgs
         End Property
 
         Public Overrides Function ToString() As String
-            Return String.Format("{{KeyCode: {0}, ScanCode: {1}, Extended: {2}, KeyState: {3}, Modifiers: {4}}}", _
-                                 Me.KeyCode, Me.ScanCode, Me.Extended, Me.KeyState, Me.Modifiers)
+            Return String.Format("{{KeyCode: {0}, ScanCode: {1}, Extended: {2}, KeyState: {3}, Modifiers: {4}, Injected: {5}, InjectedAtLowerIL: {6}}}", _
+                                 Me.KeyCode, Me.ScanCode, Me.Extended, Me.KeyState, Me.Modifiers, Me.Injected, Me.InjectedAtLowerIL)
         End Function
 
         ''' <summary>
@@ -133,5 +155,33 @@ Namespace EventArgs
             Me._keyState = KeyState
             Me._modifiers = Modifiers
         End Sub
+
+        ''' <summary>
+        ''' Initializes a new instance of the KeyboardHookEventArgs class.
+        ''' </summary>
+        ''' <param name="KeyCode">The keyboard code of the key that generated the keystroke.</param>
+        ''' <param name="ScanCode">The hardware scan code of the key that generated the keystroke.</param>
+        ''' <param name="Extended">Whether the keystroke message originated from one of the additional keys on the enhanced keyboard 
+        ''' (see: https://msdn.microsoft.com/en-us/library/windows/desktop/ms646267(v=vs.85).aspx#_win32_Keystroke_Message_Flags). </param>
+        ''' <param name="KeyState">The current state of the key that generated the keystroke.</param>
+        ''' <param name="Modifiers">The modifier keys that was pressed in combination with the keystroke.</param>
+        ''' <param name="Injected">Whether the keystroke was injected into the input stream by a process rather than an input device.</param>
+        ''' <param name="InjectedAtLowerIL">Whether the keystroke was injected into the input stream by another process running at lower integrity level.</param>
+        ''' <remarks></remarks>
+        Public Sub New(ByVal KeyCode As Keys, _
+                       ByVal ScanCode As UInteger, _
+                       ByVal Extended As Boolean, _
+                       ByVal KeyState As KeyState, _
+                       ByVal Modifiers As ModifierKeys, _
+                       ByVal Injected As Boolean, _
+                       ByVal InjectedAtLowerIL As Boolean)
+            Me._keyCode = KeyCode
+            Me._scanCode = ScanCode
+            Me._extended = Extended
+            Me._keyState = KeyState
+            Me._modifiers = Modifiers
+            Me._injected = Injected
+            Me._injectedAtLowerIL = InjectedAtLowerIL
+        End Sub
     End Class
 End Namespace

InputHelper/EventArgs/MouseEventArgs.vb

@@ -49,6 +49,8 @@ Namespace EventArgs
         Private _buttonState As KeyState
         Private _delta As Integer
         Private _doubleClick As Boolean
+        Private _injected As Boolean
+        Private _injectedAtLowerIL As Boolean
         Private _location As Point
         Private _scrollDirection As ScrollDirection
 
@@ -98,6 +100,26 @@ Namespace EventArgs
             End Get
         End Property
 
+        ''' <summary>
+        ''' Gets a boolean value indicating whether the mouse event was injected into the input stream by a process rather than an input device.
+        ''' </summary>
+        ''' <remarks></remarks>
+        Public ReadOnly Property Injected As Boolean
+            Get
+                Return _injected
+            End Get
+        End Property
+
+        ''' <summary>
+        ''' Gets a boolean value indicating whether the mouse event was injected into the input stream by another process running at lower integrity level.
+        ''' </summary>
+        ''' <remarks></remarks>
+        Public ReadOnly Property InjectedAtLowerIL As Boolean
+            Get
+                Return _injectedAtLowerIL
+            End Get
+        End Property
+
         ''' <summary>
         ''' Gets the location of the mouse (in screen coordinates).
         ''' </summary>
@@ -119,8 +141,8 @@ Namespace EventArgs
         End Property
 
         Public Overrides Function ToString() As String
-            Return String.Format("{{Button: {0}, State: {1}, DoubleClick: {2}, Location: {3}, Scroll: {4}, Delta: {5}}}", _
-                                 Me.Button, Me.ButtonState, Me.DoubleClick, Me.Location, Me.ScrollDirection, Me.Delta)
+            Return String.Format("{{Button: {0}, State: {1}, DoubleClick: {2}, Location: {3}, Scroll: {4}, Delta: {5}, Injected: {6}, InjectedAtLowerIL: {7}}}", _
+                                 Me.Button, Me.ButtonState, Me.DoubleClick, Me.Location, Me.ScrollDirection, Me.Delta, Me.Injected, Me.InjectedAtLowerIL)
         End Function
 
         ''' <summary>
@@ -146,5 +168,35 @@ Namespace EventArgs
             Me._scrollDirection = ScrollDirection
             Me._delta = Delta
         End Sub
+
+        ''' <summary>
+        ''' Initializes a new instance of the MouseHookEventArgs class.
+        ''' </summary>
+        ''' <param name="Button">Which mouse button was pressed or released.</param>
+        ''' <param name="ButtonState">The current state of the button that generated the mouse event.</param>
+        ''' <param name="DoubleClick">Whether the event was caused by a double click.</param>
+        ''' <param name="Location">The location of the mouse (in screen coordinates).</param>
+        ''' <param name="ScrollDirection">Which direction the mouse wheel was scrolled in.</param>
+        ''' <param name="Delta">A signed count of the number of detents the mouse wheel has rotated.</param>
+        ''' <param name="Injected">Whether the mouse event was injected into the input stream by a process rather than an input device.</param>
+        ''' <param name="InjectedAtLowerIL">Whether the mouse event was injected into the input stream by another process running at lower integrity level.</param>
+        ''' <remarks></remarks>
+        Public Sub New(ByVal Button As MouseButtons, _
+                       ByVal ButtonState As KeyState, _
+                       ByVal DoubleClick As Boolean, _
+                       ByVal Location As Point, _
+                       ByVal ScrollDirection As ScrollDirection, _
+                       ByVal Delta As Integer, _
+                       ByVal Injected As Boolean, _
+                       ByVal InjectedAtLowerIL As Boolean)
+            Me._button = Button
+            Me._buttonState = ButtonState
+            Me._doubleClick = DoubleClick
+            Me._location = Location
+            Me._scrollDirection = ScrollDirection
+            Me._delta = Delta
+            Me._injected = Injected
+            Me._injectedAtLowerIL = InjectedAtLowerIL
+        End Sub
     End Class
 End Namespace

InputHelper/Hooks/KeyboardHook.vb

@@ -117,6 +117,8 @@ Namespace Hooks
             Dim ScanCode As UInteger = KeystrokeInfo.scanCode
             Dim Extended As Boolean = (KeystrokeInfo.flags And NativeMethods.LowLevelKeyboardHookFlags.LLKHF_EXTENDED) = NativeMethods.LowLevelKeyboardHookFlags.LLKHF_EXTENDED
             Dim AltDown As Boolean = (KeystrokeInfo.flags And NativeMethods.LowLevelKeyboardHookFlags.LLKHF_ALTDOWN) = NativeMethods.LowLevelKeyboardHookFlags.LLKHF_ALTDOWN
+            Dim Injected As Boolean = (KeystrokeInfo.flags And NativeMethods.LowLevelKeyboardHookFlags.LLKHF_INJECTED) = NativeMethods.LowLevelKeyboardHookFlags.LLKHF_INJECTED
+            Dim InjectedAtLowerIL As Boolean = (KeystrokeInfo.flags And NativeMethods.LowLevelKeyboardHookFlags.LLKHF_LOWER_IL_INJECTED) = NativeMethods.LowLevelKeyboardHookFlags.LLKHF_LOWER_IL_INJECTED
 
             If AltDown = True _
                 AndAlso Internal.IsModifier(KeyCode, ModifierKeys.Alt) = False _
@@ -125,7 +127,7 @@ Namespace Hooks
                 Me.Modifiers = Me.Modifiers Or ModifierKeys.Alt
             End If
 
-            Return New KeyboardHookEventArgs(KeyCode, ScanCode, Extended, If(KeyDown, KeyState.Down, KeyState.Up), Me.Modifiers)
+            Return New KeyboardHookEventArgs(KeyCode, ScanCode, Extended, If(KeyDown, KeyState.Down, KeyState.Up), Me.Modifiers, Injected, InjectedAtLowerIL)
         End Function
 
         ''' <summary>

InputHelper/Hooks/MouseHook.vb

@@ -103,20 +103,23 @@ Namespace Hooks
                 Dim MouseEventInfo As NativeMethods.MSLLHOOKSTRUCT = _
                     CType(Marshal.PtrToStructure(lParam, GetType(NativeMethods.MSLLHOOKSTRUCT)), NativeMethods.MSLLHOOKSTRUCT)
 
+                Dim Injected As Boolean = (MouseEventInfo.flags And NativeMethods.LowLevelMouseHookFlags.LLMHF_INJECTED) = NativeMethods.LowLevelMouseHookFlags.LLMHF_INJECTED
+                Dim InjectedAtLowerIL As Boolean = (MouseEventInfo.flags And NativeMethods.LowLevelMouseHookFlags.LLMHF_LOWER_IL_INJECTED) = NativeMethods.LowLevelMouseHookFlags.LLMHF_LOWER_IL_INJECTED
+
                 Select Case wParam
                     Case NativeMethods.MouseMessage.WM_LBUTTONDOWN
                         Dim DoubleClick As Boolean = (Environment.TickCount - LeftClickTimeStamp) <= NativeMethods.GetDoubleClickTime()
                         LeftClickTimeStamp = Environment.TickCount
 
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.Left, KeyState.Down, DoubleClick, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseDown(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
 
                     Case NativeMethods.MouseMessage.WM_LBUTTONUP
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.Left, KeyState.Up, False, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseUp(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
@@ -126,14 +129,14 @@ Namespace Hooks
                         MiddleClickTimeStamp = Environment.TickCount
 
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.Middle, KeyState.Down, DoubleClick, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseDown(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
 
                     Case NativeMethods.MouseMessage.WM_MBUTTONUP
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.Middle, KeyState.Up, False, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseUp(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
@@ -143,14 +146,14 @@ Namespace Hooks
                         RightClickTimeStamp = Environment.TickCount
 
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.Right, KeyState.Down, DoubleClick, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseDown(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
 
                     Case NativeMethods.MouseMessage.WM_RBUTTONUP
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.Right, KeyState.Up, False, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseUp(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
@@ -163,38 +166,38 @@ Namespace Hooks
                                              Else X1ClickTimeStamp = Environment.TickCount
 
                         Dim HookEventArgs As New MouseHookEventArgs(If(IsXButton2, MouseButtons.XButton2, MouseButtons.XButton1), KeyState.Down, DoubleClick, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseDown(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
 
                     Case NativeMethods.MouseMessage.WM_XBUTTONUP
                         Dim IsXButton2 As Boolean = (New NativeMethods.DWORD(MouseEventInfo.mouseData).High = 2)
                         Dim HookEventArgs As New MouseHookEventArgs(If(IsXButton2, MouseButtons.XButton2, MouseButtons.XButton1), KeyState.Up, False, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseUp(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
 
                     Case NativeMethods.MouseMessage.WM_MOUSEWHEEL
                         Dim Delta As Integer = New NativeMethods.DWORD(MouseEventInfo.mouseData).SignedHigh
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.None, KeyState.Up, False, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.Vertical, Delta)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.Vertical, Delta, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseWheel(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
 
                     Case NativeMethods.MouseMessage.WM_MOUSEHWHEEL
                         Dim Delta As Integer = New NativeMethods.DWORD(MouseEventInfo.mouseData).SignedHigh
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.None, KeyState.Up, False, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.Horizontal, Delta)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.Horizontal, Delta, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseWheel(Me, HookEventArgs)
                         Block = HookEventArgs.Block
 
 
                     Case NativeMethods.MouseMessage.WM_MOUSEMOVE
                         Dim HookEventArgs As New MouseHookEventArgs(MouseButtons.None, KeyState.Up, False, _
-                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0)
+                                                                    New Point(MouseEventInfo.pt.x, MouseEventInfo.pt.y), ScrollDirection.None, 0, Injected, InjectedAtLowerIL)
                         RaiseEvent MouseMove(Me, HookEventArgs)
                         Block = HookEventArgs.Block