A new vulnerability, CVE-2022-2166, has been discovered in the popular open-source, federated social network Mastodon. This vulnerability allows an attacker to bypass the rules set for restricting excessive authentication attempts.

Mastodon is known for being a decentralized alternative to traditional social media platforms like Twitter. With its increasing popularity, it's crucial to ensure the security and integrity of this platform to protect its users and maintain its reputation.

This blog post will explore the details of CVE-2022-2166, including the vulnerability itself, code snippets to understand the issue better, references to the original sources, and details about how the exploit can be executed.

Vulnerability Details

CVE-2022-2166 affects the GitHub repository mastodon/mastodon before version 4... The improper restriction vulnerability arises due to the insufficient limitation on the number of failed login attempts. As a result, an attacker could abuse this vulnerability to perform credential stuffing or brute force attacks against user accounts in a Mastodon instance.

A successful exploit could potentially lead to unauthorized access to targeted user accounts, compromising user privacy and enabling further attacks using the compromised accounts.

In order to understand the vulnerability, let's look at how Mastodon handles user authentication

class AuthenticationsController < ApplicationController
  def create
    user = User.find_by(email: params[:email])

    if user && user.authenticate(params[:password])
      # Grant access to the user
    else
      # Deny access and increase failed attempts counter
    end
  end
end

As seen in the snippet, when a user tries to log in, the application checks whether the submitted email and password match any existing records. However, the problem arises when there is no restriction on the number of failed login attempts within a certain timeframe.

To mitigate this vulnerability, developers should implement a mechanism to limit the number of failed login attempts. One possible solution is to use the Devise gem, a popular and secure authentication solution for Ruby on Rails applications:

# Add this line to your Gemfile
gem 'devise'

# Install the gem
bundle install

# Generate the necessary files and modify your model
rails generate devise User

# Update your AuthenticationsController
class AuthenticationsController < Devise::SessionsController
  # ...
end

With Devise, rate limiting and account lockout after multiple failed login attempts can be easily configured, preventing attackers from exploiting this vulnerability.

To learn more about CVE-2022-2166, here are some useful references

1. National Vulnerability Database (NVD): CVE-2022-2166
2. Mastodon Repository on GitHub
3. Mastodon Security Advisory on GitHub
4. Devise Gem - Plataformatec

Conclusion

It's vital for developers and administrators of Mastodon instances to address this vulnerability and update to the latest version (4.. or later). By doing so, they significantly reduce the risks associated with unauthorized account access and the potential harm to their users.

As a Mastodon user, it's also prudent to enable two-factor authentication (2FA) on your account, which adds an extra layer of security and can provide protection against various types of account takeover attacks.

Timeline

Published on: 11/16/2022 01:15:00 UTC
Last modified on: 11/17/2022 05:00:00 UTC