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Authentication mechanism absence or evasion - Redirect

Need​

Implementation of a secure and robust authentication mechanism

Context​

  • Usage of Scala 2.11 for building scalable and high-performance applications
  • Usage of play.api.mvc for handling HTTP requests and responses in Play Framework

Description​

Non compliant code​

import play.api.mvc._

object Application extends Controller {
  
  def login = Action { implicit request =>
    val username = request.getQueryString("username")
    val password = request.getQueryString("password")

    if (username.isDefined && password.isDefined) {
      if (authenticate(username.get, password.get)) {
        Redirect(routes.Application.userHome(username.get))
      } else {
        Redirect(routes.Application.login)
      }
    } else {
      BadRequest("Missing username or password")
    }
  }

  def authenticate(username: String, password: String): Boolean = {
    // Authentication logic here
  }

  def userHome(username: String) = Action {
    Ok("Welcome " + username)
  }
}

This Scala code is using the Play framework to handle HTTP requests. The login function is an action that takes a request and checks if the username and password are defined in the query string of the request. If they are, it calls the authenticate function with these values. If the authentication is successful, it redirects the user to their home page with a Redirect response. If not, it redirects the user back to the login page.

The vulnerability here is in the Redirect response. An attacker can manipulate the username in the redirect URL to gain access to the application. Since the application does not verify the authenticity of the user after redirection, an attacker can bypass the login mechanism by knowing a valid username. This is an example of Authentication mechanism absence or evasion - Redirect vulnerability.

Steps​

  • Implement a proper authentication mechanism, such as using a secure password hashing algorithm.
  • Use a secure session management mechanism to store and validate user sessions.
  • Ensure that the login endpoint is protected against brute-force attacks by implementing rate limiting or account lockout mechanisms.
  • Implement secure redirection by validating the redirect URL and ensuring that it is a trusted and authorized destination.
  • Consider implementing multi-factor authentication to add an extra layer of security.
  • Regularly update and patch the application and its dependencies to address any security vulnerabilities.

Compliant code​

import play.api.mvc._
import play.api.libs.crypto.CookieSigner

object Application extends Controller {
  
  val cookieSigner: CookieSigner = ???

  def login = Action { implicit request =>
    val username = request.getQueryString("username")
    val password = request.getQueryString("password")

    if (username.isDefined && password.isDefined) {
      if (authenticate(username.get, password.get)) {
        val token = cookieSigner.sign(username.get)
        Redirect(routes.Application.userHome(username.get)).withSession("auth" -> token)
      } else {
        Redirect(routes.Application.login)
      }
    } else {
      BadRequest("Missing username or password")
    }
  }

  def authenticate(username: String, password: String): Boolean = {
    // Authentication logic here
    // Use a secure password hashing algorithm
  }

  def userHome(username: String) = Action { implicit request =>
    request.session.get("auth").flatMap { token =>
      if (cookieSigner.verifySignedToken(username, token)) {
        Some(Ok("Welcome " + username))
      } else {
        None
      }
    }.getOrElse(Redirect(routes.Application.login))
  }
}

The updated code now includes a secure session management mechanism. When a user logs in, a signed token is generated using the CookieSigner class provided by the Play framework. This token is then stored in the user's session.

When a user tries to access the userHome endpoint, the application checks if there is a token in the user's session. If there is, it verifies the token using the CookieSigner class. If the token is valid, the user is granted access. If the token is not valid or if there is no token, the user is redirected to the login page.

This way, even if an attacker knows a valid username, they cannot gain access to the application without the correct token. This token is only generated upon successful authentication and is securely stored in the user's session.

In addition, the authenticate method should use a secure password hashing algorithm to verify the user's password. This ensures that even if an attacker gains access to the password, they cannot reverse-engineer it to gain access to the application.

Please note that this is a basic implementation and might need to be adjusted based on your specific needs and context. For example, you might want to add rate limiting or account lockout mechanisms to protect against brute-force attacks, or implement multi-factor authentication for added security. Regularly updating and patching the application and its dependencies is also crucial to address any security vulnerabilities.

References​

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