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Use of an insecure channel - Telnet


Secure communication channel for transmitting customer information


  • Usage of Ruby for building dynamic and object-oriented applications
  • Usage of net-telnet for Telnet communication in Node.js


Non compliant code

require 'net/telnet'

host = Net::Telnet::new("Host" => "your_host",
"Timeout" => 100,
"Prompt" => /[$%#>] \\z/n)

host.cmd("username") { |c| print c }
host.cmd("password") { |c| print c }

# Sending customer information
host.cmd("Customer information") { |c| print c }

The above Ruby code snippet demonstrates the use of an insecure channel, Telnet, for transmitting customer information. The Net::Telnet class in Ruby is used to make a connection to a Telnet server.

In the code, we are creating a new Telnet object with the host name, timeout, and prompt specified. Then, we are sending commands over this connection, which include the username and password, and also the customer information.

The vulnerability here is that Telnet does not use encryption. This means that all the data sent over this connection, including the username, password, and customer information, is sent in plain text.

This is a serious security risk because anyone who is able to intercept this data transmission can easily read the data. For example, an attacker could potentially use a packet sniffer to capture the data packets being sent over the network and then read the customer information, username, and password in plain text.

Moreover, Telnet does not provide any form of authentication, which means that an attacker could potentially connect to the server and impersonate a legitimate user.

In conclusion, this code is vulnerable to data interception and unauthorized access due to its use of an insecure channel, Telnet, for data transmission.


  • Replace the use of Telnet with a secure communication protocol such as SSH or HTTPS.
  • Use a library or framework that provides built-in support for secure communication.
  • Ensure that all sensitive information, such as credentials and customer information, is transmitted over an encrypted channel.
  • Implement proper authentication and authorization mechanisms to protect customer information.
  • Regularly update and patch the software and libraries used in the application to address any security vulnerabilities.

Compliant code

require 'net/ssh'

Net::SSH.start('your_host', 'username', :password => "password") do |ssh|
# Sending customer information securely
output = ssh.exec!("Customer information")
puts output

The above code replaces the use of the insecure Telnet protocol with the secure SSH protocol for transmitting customer information. The 'net/ssh' library in Ruby provides built-in support for SSH, which is a protocol that uses encryption to secure the communication channel.

In the code, Net::SSH.start is used to start a new SSH session. The first argument is the hostname, the second argument is the username, and the password is provided as a hash option. This ensures that the credentials are not transmitted in plain text, protecting them from being captured.

The ssh.exec! method is used to send the customer information over the SSH session. The output of the command is captured and printed. This ensures that the customer information is transmitted over an encrypted channel, protecting it from being intercepted in plain text.

In addition to using a secure protocol, it's important to implement proper authentication and authorization mechanisms to further protect customer information. Regularly updating and patching the software and libraries used in the application can also help to address any security vulnerabilities.