Security hardening for 2FA configuration (#5685)

* reduce default RecentAuthenticationRequiredMixin timeout to 15 min
* never cache pages with RecentAuthenticationRequiredMixin
* show emergency codes only once after generating

src/pretix/control/templates/pretixcontrol/user/2fa_main.html

@@ -144,14 +144,23 @@
         </div>
         <div class="panel-body">
             <p>
-                {% trans "If you lose access to your devices, you can use one of the following keys to log in. We recommend to store them in a safe place, e.g. printed out or in a password manager. Every token can be used at most once." %}
+                {% blocktrans trimmed %}
+                    If you lose access to your devices, you can use one of your emergency tokens to log in.
+                    We recommend to store them in a safe place, e.g. printed out or in a password manager.
+                    Every token can be used at most once.
+                {% endblocktrans %}
             </p>
-            <p>{% trans "Unused tokens:" %}</p>
+            {% if static_tokens_device %}
-            <ul>
+                <p>
-                {% for t in static_tokens %}
+                    {% blocktrans trimmed with generation_date_time=static_tokens_device.created_at %}
-                    <li><code>{{ t.token }}</code></li>
+                        You generated your emergency tokens on {{ generation_date_time }}.
-                {% endfor %}
+                    {% endblocktrans %}
-            </ul>
+                </p>
+            {% else %}
+                <p>
+                    {% trans "You don't have any emergency tokens yet." %}
+                </p>
+            {% endif %}
             <a href="{% url "control:user.settings.2fa.regenemergency" %}" class="btn btn-default">
                 <span class="fa fa-refresh"></span>
                 {% trans "Generate new emergency tokens" %}

src/pretix/control/views/user.py

@@ -49,12 +49,14 @@ from django.db import transaction
 from django.shortcuts import get_object_or_404, redirect
 from django.urls import reverse
 from django.utils.crypto import get_random_string
+from django.utils.decorators import method_decorator
 from django.utils.functional import cached_property
 from django.utils.html import format_html
 from django.utils.http import url_has_allowed_host_and_scheme
 from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _
 from django.views import View
+from django.views.decorators.cache import never_cache
 from django.views.generic import FormView, ListView, TemplateView, UpdateView
 from django_otp.plugins.otp_static.models import StaticDevice
 from django_otp.plugins.otp_totp.models import TOTPDevice
@@ -85,8 +87,9 @@ logger = logging.getLogger(__name__)
 
 
 class RecentAuthenticationRequiredMixin:
-    max_time = 3600
+    max_time = 900
 
+    @method_decorator(never_cache)
     def dispatch(self, request, *args, **kwargs):
         tdelta = time.time() - request.session.get('pretix_auth_login_time', 0)
         if tdelta > self.max_time:
@@ -289,16 +292,13 @@ class User2FAMainView(RecentAuthenticationRequiredMixin, TemplateView):
         ctx = super().get_context_data()
 
         try:
-            ctx['static_tokens'] = StaticDevice.objects.get(user=self.request.user, name='emergency').token_set.all()
+            ctx['static_tokens_device'] = StaticDevice.objects.get(user=self.request.user, name='emergency')
         except StaticDevice.MultipleObjectsReturned:
-            ctx['static_tokens'] = StaticDevice.objects.filter(
+            ctx['static_tokens_device'] = StaticDevice.objects.filter(
                 user=self.request.user, name='emergency'
-            ).first().token_set.all()
+            ).first()
         except StaticDevice.DoesNotExist:
-            d = StaticDevice.objects.create(user=self.request.user, name='emergency')
+            ctx['static_tokens_device'] = None
-            for i in range(10):
-                d.token_set.create(token=get_random_string(length=12, allowed_chars='1234567890'))
-            ctx['static_tokens'] = d.token_set.all()
 
         ctx['devices'] = []
         for dt in REAL_DEVICE_TYPES:
@@ -631,7 +631,8 @@ class User2FARegenerateEmergencyView(RecentAuthenticationRequiredMixin, Template
         self.request.user.update_session_token()
         update_session_auth_hash(self.request, self.request.user)
         messages.success(request, _('Your emergency codes have been newly generated. Remember to store them in a safe '
-                                    'place in case you lose access to your devices.'))
+                                    'place in case you lose access to your devices. You will not be able to view them '
+                                    'again here.\n\nYour emergency codes:\n- ' + '\n- '.join(t.token for t in d.token_set.all())))
         return redirect(reverse('control:user.settings.2fa'))
 
 

src/tests/control/test_user.py

@@ -339,13 +339,17 @@ class UserSettings2FATest(SoupTest):
 
     def test_gen_emergency(self):
         self.client.get('/control/settings/2fa/')
+        assert not StaticDevice.objects.filter(user=self.user, name='emergency').exists()
+
+        self.client.post('/control/settings/2fa/regenemergency')
         d = StaticDevice.objects.get(user=self.user, name='emergency')
         assert d.token_set.count() == 10
         old_tokens = set(t.token for t in d.token_set.all())
+
         self.client.post('/control/settings/2fa/regenemergency')
-        new_tokens = set(t.token for t in d.token_set.all())
         d = StaticDevice.objects.get(user=self.user, name='emergency')
         assert d.token_set.count() == 10
+        new_tokens = set(t.token for t in d.token_set.all())
         assert old_tokens != new_tokens
 
     def test_delete_u2f(self):