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Guessed weak credentials

Need​

Enhancement of credential strength and protection

Context​

  • Usage of Java for building robust and scalable applications
  • Usage of javax.servlet for building Java web applications
  • Usage of javax.servlet.http for handling HTTP requests and responses in Java web applications

Description​

Non compliant code​

import javax.servlet.*;
import javax.servlet.http.*;

public class WeakPasswordServlet extends HttpServlet {
  private static final String USERNAME = "admin";
  private static final String PASSWORD = "password";

  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String username = request.getParameter("username");
    String password = request.getParameter("password");

    if (USERNAME.equals(username) && PASSWORD.equals(password)) {
      // authentication successful
    } else {
      // authentication failed
    }
  }
}

The above Java Servlet is vulnerable to brute force attacks due to the use of weak system credentials. The Servlet handles POST requests and retrieves the username and password parameters from the request. It then checks if these parameters match the static username and password defined in the Servlet.

The problem lies in the fact that the static username and password are both weak, simple and easily guessable. The username is "admin" and the password is "password". These are common credentials that are often used in default configurations and are therefore the first ones that an attacker would try in a brute force attack.

A brute force attack involves trying every possible combination of credentials until the correct one is found. The simplicity and predictability of the credentials in this Servlet greatly reduce the amount of time required to guess them, making the system highly vulnerable to such attacks.

Furthermore, the credentials are hard-coded into the Servlet, meaning that they cannot be easily changed without modifying the source code. This is a bad practice as it doesn't allow for flexibility in changing the credentials and it exposes sensitive information in the source code.

In summary, the use of weak and static credentials in this Servlet makes it vulnerable to brute force attacks. To fix this vulnerability, stronger and dynamic credentials should be used, and they should not be hard-coded into the source code.

Steps​

  • Avoid using weak and easily guessable credentials.
  • Implement a strong password policy that enforces the use of complex passwords.
  • Use a secure password hashing algorithm to store passwords.
  • Implement account lockout mechanisms to prevent brute force attacks.
  • Implement rate limiting to restrict the number of login attempts within a certain time period.
  • Implement multi-factor authentication to add an extra layer of security.
  • Regularly update and patch the system to fix any known vulnerabilities.
  • Educate users about the importance of choosing strong passwords and avoiding password reuse.

Compliant code​

import javax.servlet.*;
import javax.servlet.http.*;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

public class SecurePasswordServlet extends HttpServlet {
  private static final String USERNAME = "admin";
  private static final String PASSWORD = hashPassword("StrongPassword123!"); // Replace with a strong password
  private static final int MAX_ATTEMPTS = 5;
  private static int loginAttempts = 0;

  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    if (loginAttempts >= MAX_ATTEMPTS) {
      response.sendError(HttpServletResponse.SC_FORBIDDEN, "Too many failed attempts. Please try again later.");
      return;
    }

    String username = request.getParameter("username");
    String password = hashPassword(request.getParameter("password"));

    if (USERNAME.equals(username) && PASSWORD.equals(password)) {
      // authentication successful
      loginAttempts = 0;
    } else {
      // authentication failed
      loginAttempts++;
    }
  }

  private static String hashPassword(String password) {
    try {
      MessageDigest md = MessageDigest.getInstance("SHA-256");
      byte[] hashedBytes = md.digest(password.getBytes());
      return new String(hashedBytes);
    } catch (NoSuchAlgorithmException e) {
      throw new RuntimeException(e);
    }
  }
}

The updated code includes several security enhancements to mitigate the risk of brute force attacks and weak credentials.

  1. Strong Password: The PASSWORD constant is now set to a hashed version of a strong password. This password should be complex, including a mix of uppercase and lowercase letters, numbers, and special characters.

  2. Password Hashing: The hashPassword method is used to create a SHA-256 hash of the password. This ensures that even if the password data is somehow compromised, the actual password is not easily recoverable.

  3. Account Lockout: The loginAttempts variable is used to track the number of failed login attempts. If the number of failed attempts reaches a maximum limit (in this case, 5), the system will not allow any more attempts and will send a "Forbidden" error.

  4. Rate Limiting: By limiting the number of login attempts, we effectively implement a form of rate limiting. This restricts the number of login attempts within a certain time period, making brute force attacks more difficult.

Remember, this is just a basic example. In a real-world application, you would also want to implement additional security measures such as multi-factor authentication, regular system updates and patches, and user education about the importance of strong passwords and avoiding password reuse.

References​

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