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Use of an insecure channel - Telnet

Need​

Secure transmission of customer information

Context​

  • Usage of Java for building robust and scalable applications
  • Usage of javax.servlet for building Java web applications with Servlet technology
  • Usage of java.io for input and output operations in Java

Description​

Non compliant code​

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class InsecureChannelServlet extends HttpServlet {
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // Use Telnet to transmit customer information
        ProcessBuilder processBuilder = new ProcessBuilder("telnet", "example.com", "23");
        Process process = processBuilder.start();

        OutputStream outputStream = process.getOutputStream();
        outputStream.write((username + "\\n" + password + "\\n").getBytes());
        outputStream.flush();
    }
}

The above Java code represents a Servlet that handles a POST request. It retrieves the username and password parameters from the request. These parameters are likely to be the credentials of a customer.

The Servlet then starts a new process to run the telnet command, which connects to a remote host example.com on port 23. The username and password are written to the process's output stream, which is transmitted to the remote host over the insecure Telnet protocol.

The vulnerability lies in the use of Telnet, an insecure protocol that does not encrypt its communications. This means that the customer's username and password are transmitted in plain text over the network. Anyone who can intercept this network traffic, such as an attacker on the same network, can easily read these credentials and potentially misuse them.

The use of an insecure channel like Telnet for transmitting sensitive information is a serious security flaw. It does not maintain the confidentiality of the transmitted information, thus exposing it to potential eavesdropping and compromising the security of the customer's account.

Steps​

  • Replace the use of Telnet with a secure channel, such as HTTPS.
  • Use encryption to protect the transmission of customer information.
  • Implement SSL/TLS to establish a secure connection between the client and the server.
  • Ensure that the server has a valid SSL/TLS certificate.
  • Implement proper authentication and authorization mechanisms to protect customer credentials.
  • Implement secure coding practices to prevent other vulnerabilities.

Compliant code​

import javax.net.ssl.HttpsURLConnection;
import java.io.*;
import java.net.URL;

public class SecureChannelServlet extends HttpServlet {
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // Use HTTPS to transmit customer information
        URL url = new URL("https://example.com");
        HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();

        // Enable input and output streams
        conn.setDoInput(true);
        conn.setDoOutput(true);

        // Set request method to POST
        conn.setRequestMethod("POST");

        // Send post request
        DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
        wr.writeBytes("username=" + username + "&password=" + password);
        wr.flush();
        wr.close();
    }
}

The above code fixes the vulnerability by replacing the use of Telnet with HTTPS, a secure channel.

The HttpsURLConnection class is used to create a secure connection to the server. The setDoInput(true) and setDoOutput(true) methods are used to enable input and output streams. The setRequestMethod("POST") method is used to set the request method to POST.

The DataOutputStream class is used to send the POST request. The writeBytes method is used to write the username and password to the output stream. The flush method is used to flush the output stream, and the close method is used to close the output stream.

This code ensures that customer information is transmitted over a secure channel, protecting it from being captured in plain text. It also implements SSL/TLS to establish a secure connection between the client and the server.

Please ensure that the server has a valid SSL/TLS certificate. Also, implement proper authentication and authorization mechanisms to protect customer credentials. Lastly, always follow secure coding practices to prevent other vulnerabilities.

References​

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