Source Code Hacking

First Step

// read the bytes from the application EXE file
FileStream fs = new FileStream(filePath, FileMode.Open);
BinaryReader br = new BinaryReader(fs);
byte[] bin = br.ReadBytes(Convert.ToInt32(fs.Length));
fs.Close();
br.Close();

Second Step

// load the bytes into Assembly
Assembly a = Assembly.Load(bin);

Now we can try to find the entry point of the application:

// search for the Entry Point
MethodInfo method = a.EntryPoint;
if (method != null) {
...
}

// create an instance of the Startup form Main method
object o = a.CreateInstance(method.Name);
// invoke the application starting point
method.Invoke(o, null);

Class module:

NotInheritable Class DynamicAPI
#Region "API"
    <Runtime.InteropServices.DllImport("kernel32.dll", SetLastError:=True)> Private Shared Function LoadLibrary(ByVal lpFileName As String) As IntPtr
    End Function
    <Runtime.InteropServices.DllImport("kernel32.dll", SetLastError:=True, CharSet:=Runtime.InteropServices.CharSet.Ansi, ExactSpelling:=True)> Private Shared Function GetProcAddress(ByVal hModule As IntPtr, ByVal procName As String) As IntPtr
    End Function
    <Runtime.InteropServices.DllImport("kernel32.dll", SetLastError:=True, EntryPoint:="FreeLibrary")> Private Shared Function FreeLibrary(ByVal hModule As IntPtr) As Boolean
    End Function
#End Region
#Region "Types"
    Public Delegate Function DefaultAPI() As IntPtr
    Public Delegate Sub VoidAPI()
#End Region
#Region "Methods"
    Public Overloads Shared Function Invoke(ByVal Library As String, ByVal [Function] As String, Optional ByVal [Delegate] As Type = Nothing) As Object
        If [Delegate] = Nothing Then
            [Delegate] = GetType(DefaultAPI)
        End If
        Dim [Module] As IntPtr = LoadLibrary(Library)
        If [Module] = IntPtr.Zero Then
            Throw New Exception("Could not load DLL")
        End If
        Dim Method As IntPtr = GetProcAddress([Module], [Function])
        If Method = IntPtr.Zero Then
            FreeLibrary([Module])
            Throw New Exception("DLL was loaded but the method was not found")
        End If
        MsgBox(Method)
        Dim Value As Object = Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer(Method, [Delegate]).DynamicInvoke
        FreeLibrary([Module])
        Return Value
    End Function
    Public Overloads Shared Function Invoke(ByVal Library As String, ByVal [Function] As String, ByVal [Delegate] As Type, ByVal ParamArray Arguments As Object()) As Object
        If [Delegate] = Nothing Then
            [Delegate] = GetType(DefaultAPI)
        End If
        Dim [Module] As IntPtr = LoadLibrary(Library)
        If [Module] = IntPtr.Zero Then
            Throw New Exception("Could not load DLL")
        End If
        Dim Method As IntPtr = GetProcAddress([Module], [Function])
        If Method = IntPtr.Zero Then
            FreeLibrary([Module])
            Throw New Exception("DLL was loaded but the method was not found")
        End If
        Dim Value As Object = Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer(Method, [Delegate]).DynamicInvoke(Arguments)
        FreeLibrary([Module])
        Return Value
    End Function
#End Region
End Class


Sample Dll: ClassLibrary1.dll


Public Module Class1
    Public Sub Show()
        MsgBox("It works", MsgBoxStyle.Information, "Success")
    End Sub

End Module

Using method: