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JSP安全開發(fā)之XSS漏洞詳解

 更新時(shí)間:2016年09月13日 18:21:47   作者:0nise  
XSS又叫CSS (Cross Site Script) ,跨站腳本攻擊。它指的是惡意攻擊者往Web頁(yè)面里插入惡意腳本代碼,而程序?qū)τ谟脩糨斎雰?nèi)容未過濾,當(dāng)用戶瀏覽該頁(yè)之時(shí),嵌入其中Web里面的腳本代碼會(huì)被執(zhí)行,從而達(dá)到惡意攻擊用戶的特殊目的。

前言

     大家好,好男人就是我,我就是好男人,我就是-0nise。在各大漏洞舉報(bào)平臺(tái),我們時(shí)常會(huì)看到XSS漏洞。那么問題來了,為何會(huì)出現(xiàn)這種漏洞?出現(xiàn)這種漏洞應(yīng)該怎么修復(fù)?

正文

1.XSS?XSS?XSS是什么鬼?

     XSS又叫跨站腳本攻擊(Cross Site Scripting),我不會(huì)告訴他原本是叫CSS的,但是為了不和我們所用的層疊樣式表(Cascading Style Sheets)CSS搞混。CSS(跨站腳本攻擊),CSS(層疊樣式表)傻傻分不清。所以就叫XSS咯。

2.XSS的危害是什么?

實(shí)驗(yàn)一:

0x00構(gòu)造代碼

<%@ 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">
 <%
//設(shè)置編碼
   request.setCharacterEncoding("UTF-8");
//接收用戶傳入值
   String tmp = request.getParameter("opr");
   //減速傳入值是否為空
   if(tmp == null){
     out.print("111");
   }else{
     //轉(zhuǎn)碼
     String opr = new String(tmp.getBytes("ISO-8859-1"),"utf-8");
     out.print(opr);
   }
 %>
   我是內(nèi)容
 </div>
 </body>
</html>

0x01環(huán)境布局

0x02漏洞演練

我們?cè)L問:http://localhost:8080/XSS/index.jsp?opr=i%E6%98%A5%E7%A7%8B

然后訪問:http://localhost:8080/XSS/index.jsp?opr=0nise

最后我們發(fā)現(xiàn)了一個(gè)“偉大的規(guī)律”:

   opr參數(shù)等于什么頁(yè)面就打印什么。(好像是廢話)

我們接著來加載一個(gè)圖片看看

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

既然圖片都可以加載,那么我們JS文件是不是也闊以加載呢?

訪問: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?那么是不是可以來改變跳轉(zhuǎn)后地址?

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

既然xss都可以加載js,那么,我們是不是通過js來打開本地的某些東西?

提前放了一個(gè)MD5.exe文件

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

既然連本地文件都可以打開那么遠(yuǎn)程文件木馬?來個(gè)電腦惡搞?這個(gè)自己慢慢象限。我可沒說啊。。。。。

文件都可以打開,那么寫一些文件呢?

訪問: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

通過以上實(shí)驗(yàn)我們可以看出opr參數(shù)賦值操作。如果opr參數(shù)沒有值的話,就無法執(zhí)行執(zhí)行,被攻擊者必須訪問攻擊者提前設(shè)計(jì)好的才能攻擊。這種XSS攻擊方式叫做:存儲(chǔ)型XSS

如果你想看到更給力的實(shí)驗(yàn),請(qǐng)接著往下看。

實(shí)驗(yàn)二:

前言:

大部分網(wǎng)站都會(huì)和數(shù)據(jù)打交道那么,XSS漏洞出現(xiàn)這些網(wǎng)站是什么樣子的?

0x00構(gòu)造代碼

數(shù)據(jù)庫(kù)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 {
  //打開連接
  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;
  }
   
  //關(guān)閉鏈接的方法
  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();
    }
  }
  //重載關(guān)閉方法
  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();
    }
  }
  //繼續(xù)重載
  public void closeAll(Connection conn,PreparedStatement pstat){
    try {
      if(pstat != null)
        pstat.close();
      if(conn != null)
        conn.close();
    } catch (SQLException e) {
      e.printStackTrace();
    }
  }
  //增刪改的公用方法
  public int upDate(String sql,Object[] pram){
     
    PreparedStatement pstat = null;
    Connection conn = null;
    int a = 0;
     
    try {
      conn = getConn();
      pstat =conn.prepareStatement(sql);
      //遍歷參數(shù)集合,將集合中的參數(shù)對(duì)應(yīng)添加到sql語(yǔ)句中
      for (int i = 1; i <= pram.length; i++) {
        pstat.setObject(i, pram[i-1]);
      }
      //調(diào)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 {
  /**
   * 獲取所有留言
   * */
  public List<comm> GetComment(){
    //SQL語(yǔ)句
    String sql = "SELECT CID,CName,CContext FROM Comments";
    List<comm> list = new ArrayList<comm>();
    //數(shù)據(jù)庫(kù)連接對(duì)象
    Connection conn = null;
    //SQL執(zhí)行對(duì)象
    PreparedStatement pstmt = null;
    //數(shù)據(jù)庫(kù)執(zhí)行返回值
    ResultSet rs = null;
    try {
      //創(chuàng)建數(shù)據(jù)庫(kù)鏈接
      conn = this.getConn();
      //創(chuàng)建SQL執(zhí)行對(duì)象
      pstmt = conn.prepareStatement(sql);
      //執(zhí)行SQL語(yǔ)句  返回值
      rs = pstmt.executeQuery();
      //讀取
      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{
      //關(guān)閉
      this.closeAll(conn, pstmt, rs);
    }
    return list;
  }
  public int AddComment(comm comment){
    String sql = "INSERT INTO Comments VALUES(?,?)";
    //受影響行數(shù)
    int result = 0;  
    //數(shù)據(jù)庫(kù)連接對(duì)象
    Connection conn = null;
    //SQL執(zhí)行對(duì)象
    PreparedStatement pstmt = null;
    try {
      //創(chuàng)建數(shù)據(jù)庫(kù)鏈接
      conn = this.getConn();
      //創(chuàng)建SQL執(zhí)行對(duì)象
      pstmt = conn.prepareStatement(sql);
      //設(shè)置參數(shù)
      pstmt.setString(1, comment.getCName());
      pstmt.setString(2, comment.getCContext());
      //執(zhí)行SQL語(yǔ)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();
    //檢索參數(shù)是否為空
    if(opr == null || opr.equals("all")){
      request.setAttribute("all", commentDao.GetComment());
      //轉(zhuǎn)發(fā)
      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('留言失敗');location.href='CommentServlvet?opr=all';</script>");
      }
    }else{
      request.setAttribute("all", commentDao.GetComment());
      //轉(zhuǎn)發(fā)
      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>
   昵稱:<input type="text" name="UName" />
   <input type="submit" value="提交" />
 </form>
 </body>
</html>

0x01漏洞實(shí)驗(yàn)

root@1~#

我們?cè)诹粞园辶粞裕?/p>

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

然后訪問:http://localhost:8080/XSS/comment.jsp

這樣只要訪問這個(gè)頁(yè)面,軟件就自動(dòng)打開了,來個(gè)遠(yuǎn)程文件?慢慢領(lǐng)悟。

root@2~#

我們?cè)诹粞园辶粞裕?/p>

復(fù)制代碼 代碼如下:
<script>var fso,tf;fso = new ActiveXObject("Scripting.FileSystemObject");tf = fso.CreateTextFile("d:\\test.txt",true);tf.WriteLine("i春秋社區(qū)歡迎您");tf.Close();alert("文件寫入成功!");</script>

然后訪問: http://localhost:8080/XSS/comment.jsp

文件寫入成功。

root@3~#

留言內(nèi)容:

[code]<script>location.</script>[code]

訪問頁(yè)面:http://localhost:8080/XSS/comment.jsp

訪問留言頁(yè)面自動(dòng)跳轉(zhuǎn)到攻擊者特定的網(wǎng)站。難道這就是傳說中的劫持嗎?

3.XSS防御方案

正所謂哪里有攻擊,哪里就有防御。XSS一樣,有攻擊的方式,也有防御的方案。

EL表達(dá)式+JSTL標(biāo)簽庫(kù)

EL(Expression Language):[size=12.0000pt]為了使JSP寫起來更簡(jiǎn)單。表達(dá)式語(yǔ)言的靈感來自于ECMAScript和XPath表達(dá)式語(yǔ)語(yǔ)言,他提供了JSP中簡(jiǎn)化表達(dá)式的方法,讓jsp代碼更簡(jiǎn)單。

JSTL(JSP Standard Tag Library):開放源代碼的JSP標(biāo)簽庫(kù)。

實(shí)驗(yàn)一防御代碼:

<%@ 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");
   //減速傳入值是否為空
   if(tmp == null){
     out.print("111");
   }else{
     //轉(zhuǎn)碼
     String opr = new String(tmp.getBytes("ISO-8859-1"),"utf-8");
     request.setAttribute("name", opr);
     %>
     <c:out value="${requestScope.name }"></c:out>
     <%
   }
 %>
   我是內(nèi)容
 </div>
 </body>
</html>

實(shí)驗(yàn)二防御代碼:

<%@ 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>
   昵稱:<input type="text" name="UName" />
   <input type="submit" value="提交" />
 </form>
 </body>
</html>

結(jié)束語(yǔ)

        技術(shù)無黑白,專研甚好。

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