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Use of an insecure channel - Telnet

Need​

Secure communication channel for transmitting customer information

Context​

  • Usage of Scala for building scalable and functional applications
  • Usage of Play Framework for building web applications in Scala or Java
  • Usage of java.net.Socket for network communication
  • Usage of java.io.* for input/output operations in Java

Description​

Non compliant code​

import java.net.Socket
import java.io._
import play.api._
import play.api.mvc._

// Controller for handling requests
class HomeController extends Controller {
  def sendInfo = Action { request =>
    val socket = new Socket("localhost", 23)
    val out = new PrintWriter(socket.getOutputStream, true)
    val in = new BufferedReader(new InputStreamReader(socket.getInputStream))

    // Sending customer information over insecure Telnet channel
    out.println("Customer Username: " + request.body.asFormUrlEncoded.get("username").mkString)
    out.println("Customer Password: " + request.body.asFormUrlEncoded.get("password").mkString)

    socket.close()
    Ok("Information sent")
  }
}

The above Scala code snippet is a part of a Play Framework backend application. It represents a controller named HomeController that has a method sendInfo, which is used to send customer data.

The vulnerability lies in the sendInfo method where it opens a socket to a localhost on port 23, which is the default port for Telnet. Telnet is an insecure protocol as it does not encrypt its data. This means that any data sent over this protocol can be easily captured in plain text.

The method then creates a PrintWriter for sending data over the socket and a BufferedReader for reading data from the socket. The customer's username and password are then retrieved from the request body and sent over the Telnet channel using the PrintWriter.

The use of Telnet to transmit sensitive information such as usernames and passwords constitutes a major security vulnerability. An attacker can easily intercept the data transmission and gain unauthorized access to the customer's information.

Steps​

  • Replace the insecure Telnet channel with a secure channel that uses encryption, such as HTTPS.
  • Use a secure communication protocol, such as TLS/SSL, to encrypt the data transmitted over the channel.
  • Update the code to use a secure socket implementation, such as SSLSocket, instead of the plain Socket class.
  • Obtain a valid SSL certificate for the server to ensure secure communication.
  • Configure the server to use the secure channel and enforce HTTPS for all requests.
  • Ensure that the client-side code also uses HTTPS when making requests to the server.
  • Implement proper authentication and authorization mechanisms to protect customer information.
  • Consider using additional security measures, such as encryption of sensitive data at rest and in transit.

Compliant code​

import java.net.Socket
import javax.net.ssl.{SSLSocketFactory, SSLSocket}
import java.io._
import play.api._
import play.api.mvc._

// Controller for handling requests
class HomeController extends Controller {
  def sendInfo = Action { request =>
    val socketFactory: SSLSocketFactory = SSLSocketFactory.getDefault().asInstanceOf[SSLSocketFactory]
    val socket: SSLSocket = socketFactory.createSocket("localhost", 443).asInstanceOf[SSLSocket]
    val out = new PrintWriter(socket.getOutputStream, true)
    val in = new BufferedReader(new InputStreamReader(socket.getInputStream))

    // Sending customer information over secure SSL channel
    out.println("Customer Username: " + request.body.asFormUrlEncoded.get("username").mkString)
    out.println("Customer Password: " + request.body.asFormUrlEncoded.get("password").mkString)

    socket.close()
    Ok("Information sent")
  }
}

The updated code replaces the insecure Telnet channel with a secure SSL channel. The Socket class is replaced with SSLSocket, which is a secure socket using SSL/TLS protocols to encrypt the data transmitted over the channel.

The SSLSocketFactory is used to create the SSLSocket. The SSLSocketFactory is obtained by calling the getDefault method, which returns the default SSL socket factory. The default SSL socket factory is determined by the system property javax.net.ssl.SSLSocketFactory. If this system property is not set, the default SSL socket factory is an instance of javax.net.ssl.SSLSocketFactory.

The SSLSocket is created by calling the createSocket method on the SSLSocketFactory, passing the server's hostname and port number as arguments. The port number is changed from 23 (the default port for Telnet) to 443 (the default port for HTTPS).

The customer's username and password are sent over the secure SSL channel by calling the println method on the PrintWriter object, which is created by passing the SSLSocket's output stream to the PrintWriter constructor.

The SSLSocket is closed after the customer's information is sent.

The server must be configured to use the secure channel and enforce HTTPS for all requests. The client-side code must also use HTTPS when making requests to the server. Proper authentication and authorization mechanisms should be implemented to protect customer information. Additional security measures, such as encryption of sensitive data at rest and in transit, should be considered.

References​

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