CODEWITHSUNDEEP
javascriptjavaglassfishderby
CreativeXtent
CreativeXtent

Reputation: 59

I am not sure how to perform html escaping in my java project to prevent XSS

Just a note, this is for class. I would go to the class material, but it doesn't address this(the school is kinda garbage). And when i ask the teacher, he says to google it. I've tried googling it, but my understanding is not good enough yet sadly.

My setup is as follows. Its a web application that uses DerbyDB, Glassfish 5, Java and javascript servlets.

I know this is answered 100000 times on here, but being as dense as i am... i am not getting it. i have a java web application (without maven). The login uses login.jsp and authenticates through authenticate.java of course there is no escaping so its vulnerable to xss. I am just not sure how to implement this. If someone could guide me there. If there is a library or something to load and if so how to use it.

login.jsp

<%-- 
    Document   : login
    Created on : Aug 10, 2015, 7:53:14 PM
    Author     : jim
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <title>SDEV425 Login</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <link href="styles.css" rel="stylesheet" type="text/css">
    </head>
    <body>
        <div id="main">
            <%@include file="WEB-INF/jspf/menus.jspf" %>
            <p></p>
            <p></p>
            <h2>Login</h2>

            <% if (session.getAttribute("UMUCUserEmail") == null) {
            %>



            <form action="Authenticate" method="post">
                <table class="center">
                    <tr>
                    <td>Email: </td><td><input type="text"  name="emailAddress"  size="50" autofocus> </td>
                    </tr>
                    <tr>
                        <td>
                            Password: </td><td><input type="password" name="pfield" size="50" autocomplete="off"></td>
                    </tr>
                    <tr>
                        <td>
                            &nbsp;
                        </td>
                        <td>
                            <input type="submit" name="SignIn" value="Sign In">
                        </td>
                    </tr>
                </table>
                <p></p>
                <!-- Print Error Message if any -->
                <% String e = (String) request.getAttribute("ErrorMessage");
                    if (e != null) {
                        out.print(e);
                    }
                %>

            </form>
            <%
                } else {

                    request.setAttribute("ErrorMessage", "You are already logged in.");
                    RequestDispatcher dispatcher = request.getRequestDispatcher("welcome.jsp");
                    dispatcher.forward(request, response);                    
                }
            %>
        </div>
    </body>
</html>

Authenticate.java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package SDEV425_HW4;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.PreparedStatement;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.derby.jdbc.ClientDataSource;



/**
 *
 * @author jim
 */
public class Authenticate extends HttpServlet {

    // variables    
    private String username;
    private String pword;
    private Boolean isValid;
    private int user_id;
    private HttpSession session;

    
    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet Authenticate</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet Authenticate at " + request.getContextPath() + "</h1>");
            
            out.println("</body>");
            out.println("</html>");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        // Get the post input 
        this.username = request.getParameter("emailAddress");
        this.pword = request.getParameter("pfield");
        this.isValid = validate(this.username, this.pword);
         response.setContentType("text/html;charset=UTF-8");
        // Set the session variable
        if (isValid) {
            // Create a session object if it is already not  created.
            session = request.getSession(true);
            session.setAttribute("UMUCUserEmail", username);         
            session.setAttribute("UMUCUserID", user_id);

            // Send to the Welcome JSP page              
            
            RequestDispatcher dispatcher = request.getRequestDispatcher("welcome.jsp");
            dispatcher.forward(request, response);

        } else {
            // Not a valid login
            // refer them back to the Login screen

            request.setAttribute("ErrorMessage", "Invalid Username or Password. Try again or contact Jim.");
            RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
            dispatcher.forward(request, response);
        }
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

    // Method to Authenticate
    public boolean validate(String name, String pass) {
        boolean status = false;
        int hitcnt=0;

        try {
            ClientDataSource ds = new ClientDataSource();
            ds.setDatabaseName("SDEV425");
            ds.setServerName("localhost");
            ds.setPortNumber(1527);
            ds.setUser("sdev425");
            ds.setPassword("sdev425");
            ds.setDataSourceName("jdbc:derby");

            Connection conn = ds.getConnection();

           
            
            String sql = "select user_id from sdev_users  where EMAIL = ?";
            PreparedStatement stmt = conn.prepareStatement(sql);
            stmt.setString(1, this.username); 
            
            
            ResultSet rs = stmt.executeQuery();
            
            while (rs.next()) {
                user_id = rs.getInt(1);
            }
            if (user_id> 0) {                
                
                String sql2 = "select user_id from user_info where user_id = " + user_id + "and password = ?";

                
                PreparedStatement stmt2 = conn.prepareStatement(sql2);
                stmt2.setString(1, this.pword);
                
                ResultSet rs2 = stmt2.executeQuery();
                
                while (rs2.next()) {
                    hitcnt++;
                }   
                // Set to true if userid/password match
               if(hitcnt>0){
                   status=true;
               }
            }

        } catch (Exception e) {
            System.out.println(e);
        }
        return status;
    }

}

Upvotes: 0

Views: 895

Answers (1)

Abdul
Abdul

Reputation: 149

You can use StringEscapeUtils.escapeHtml4() method.

import org.apache.commons.text.StringEscapeUtils;
 
public class HTMLEscapeExample 
{
    public static void main(String[] args) 
    {
        String unEscapedString = "<html>some-random-text</html>";
         
        String escapedHTML = StringEscapeUtils.escapeHtml4(unEscapedString);
         
        System.out.println(escapedHTML);    //Browser can now parse this and print
    }
}
 
//Output:
 
&lt;html&gt;some-random-text&lt;/html&gt;

Upvotes: 2

Related Questions