Commit 4a9f5ef9 authored by Rémy Coutable's avatar Rémy Coutable 🏔 Committed by Rémy Coutable

Merge branch 'fix/2fa-authentication-spoofing' into 'master'

Fix 2FA authentication spoofing

This is security fix for vulnerability described at
https://gitlab.com/gitlab-org/gitlab-ce/issues/14900.

Attacker was able to bypass password authentication of users that have 2FA enabled, and consequently sign is as a different user, without knowing his password, if he managed to guess 2FA One Time Password for that user.

It was also possible to enumerate users and check if they have 2FA enabled, because GitLab responded with different error for each case.

This MR attempts to change default user search scope if `otp_user_id` session variable has been set. If it is present, it means that user has 2FA enabled, and has already been verified with login and password. In this case we should look for user with `otp_user_id` first, before picking it up by `login`.

Both, 2FA authentication spoofing and 2FA discovery have been covered by specs.

Current 2FA code is a bit tricky, so it probably needs some refactoring.
Signed-off-by: Rémy Coutable's avatarRémy Coutable <remy@rymai.me>
parent 2b060c64
Pipeline #1544031 failed with stage
Please view this file on the master branch, on stable branches it's out of date.
v 8.5.10
- Fix a 2FA authentication spoofing vulnerability.
v 8.5.9
- Don't attempt to fetch any tags from a forked repo (Stan Hu). !3504
......
......@@ -4,7 +4,8 @@ class SessionsController < Devise::SessionsController
skip_before_action :check_2fa_requirement, only: [:destroy]
prepend_before_action :authenticate_with_two_factor, only: [:create]
prepend_before_action :authenticate_with_two_factor,
if: :two_factor_enabled?, only: [:create]
prepend_before_action :store_redirect_path, only: [:new]
before_action :auto_sign_in_with_provider, only: [:new]
before_action :load_recaptcha
......@@ -38,10 +39,10 @@ class SessionsController < Devise::SessionsController
end
def find_user
if user_params[:login]
User.by_login(user_params[:login])
elsif user_params[:otp_attempt] && session[:otp_user_id]
if session[:otp_user_id]
User.find(session[:otp_user_id])
elsif user_params[:login]
User.by_login(user_params[:login])
end
end
......@@ -65,11 +66,13 @@ class SessionsController < Devise::SessionsController
end
end
def two_factor_enabled?
find_user.try(:two_factor_enabled?)
end
def authenticate_with_two_factor
user = self.resource = find_user
return unless user && user.two_factor_enabled?
if user_params[:otp_attempt].present? && session[:otp_user_id]
if valid_otp_attempt?(user)
# Remove any lingering user data from login
......
require 'spec_helper'
describe SessionsController do
describe '#create' do
before do
@request.env['devise.mapping'] = Devise.mappings[:user]
end
context 'when using standard authentications' do
context 'invalid password' do
it 'does not authenticate user' do
post(:create, user: { login: 'invalid', password: 'invalid' })
expect(response)
.to set_flash.now[:alert].to /Invalid login or password/
end
end
context 'when using valid password' do
let(:user) { create(:user) }
it 'authenticates user correctly' do
post(:create, user: { login: user.username, password: user.password })
expect(response).to set_flash.to /Signed in successfully/
expect(subject.current_user). to eq user
end
end
end
context 'when using two-factor authentication' do
let(:user) { create(:user, :two_factor) }
def authenticate_2fa(user_params)
post(:create, { user: user_params }, { otp_user_id: user.id })
end
##
# See #14900 issue
#
context 'when authenticating with login and OTP of another user' do
context 'when another user has 2FA enabled' do
let(:another_user) { create(:user, :two_factor) }
context 'when OTP is valid for another user' do
it 'does not authenticate' do
authenticate_2fa(login: another_user.username,
otp_attempt: another_user.current_otp)
expect(subject.current_user).to_not eq another_user
end
end
context 'when OTP is invalid for another user' do
it 'does not authenticate' do
authenticate_2fa(login: another_user.username,
otp_attempt: 'invalid')
expect(subject.current_user).to_not eq another_user
end
end
context 'when authenticating with OTP' do
context 'when OTP is valid' do
it 'authenticates correctly' do
authenticate_2fa(otp_attempt: user.current_otp)
expect(subject.current_user).to eq user
end
end
context 'when OTP is invalid' do
before { authenticate_2fa(otp_attempt: 'invalid') }
it 'does not authenticate' do
expect(subject.current_user).to_not eq user
end
it 'warns about invalid OTP code' do
expect(response).to set_flash.now[:alert]
.to /Invalid two-factor code/
end
end
end
context 'when another user does not have 2FA enabled' do
let(:another_user) { create(:user) }
it 'does not leak that 2FA is disabled for another user' do
authenticate_2fa(login: another_user.username,
otp_attempt: 'invalid')
expect(response).to set_flash.now[:alert]
.to /Invalid two-factor code/
end
end
end
end
end
end
end
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