security: fix oobe-flow reuse when akadmin is deleted (#7361)

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

authentik/flows/migrations/0027_auto_20231028_1424.py

@@ -0,0 +1,34 @@
+# Generated by Django 4.2.6 on 2023-10-28 14:24
+
+from django.apps.registry import Apps
+from django.db import migrations
+from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+
+
+def set_oobe_flow_authentication(apps: Apps, schema_editor: BaseDatabaseSchemaEditor):
+    from guardian.shortcuts import get_anonymous_user
+
+    Flow = apps.get_model("authentik_flows", "Flow")
+    User = apps.get_model("authentik_core", "User")
+
+    db_alias = schema_editor.connection.alias
+
+    users = User.objects.using(db_alias).exclude(username="akadmin")
+    try:
+        users = users.exclude(pk=get_anonymous_user().pk)
+    # pylint: disable=broad-except
+    except Exception:  # nosec
+        pass
+
+    if users.exists():
+        Flow.objects.filter(slug="initial-setup").update(authentication="require_superuser")
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("authentik_flows", "0026_alter_flow_options"),
+    ]
+
+    operations = [
+        migrations.RunPython(set_oobe_flow_authentication),
+    ]

blueprints/default/flow-oobe.yaml

@@ -85,6 +85,19 @@ entries:
   identifiers:
     name: default-oobe-password-usable
   model: authentik_policies_expression.expressionpolicy
+- attrs:
+    expression: |
+      # This policy ensures that the setup flow can only be
+      # used one time
+      from authentik.flows.models import Flow, FlowAuthenticationRequirement
+      Flow.objects.filter(slug="initial-setup").update(
+          authentication=FlowAuthenticationRequirement.REQUIRE_SUPERUSER,
+      )
+      return True
+  id: policy-default-oobe-flow-set-authentication
+  identifiers:
+    name: default-oobe-flow-set-authentication
+  model: authentik_policies_expression.expressionpolicy
 - attrs:
     fields:
     - !KeyOf prompt-field-header
@@ -129,6 +142,7 @@ entries:
     evaluate_on_plan: true
     invalid_response_action: retry
     re_evaluate_policies: false
+  id: binding-login
   identifiers:
     order: 100
     stage: !KeyOf stage-default-authentication-login
@@ -144,3 +158,8 @@ entries:
     policy: !KeyOf policy-default-oobe-prefill-user
     target: !KeyOf binding-password-write
   model: authentik_policies.policybinding
+- identifiers:
+    order: 0
+    policy: !KeyOf policy-default-oobe-flow-set-authentication
+    target: !KeyOf binding-login
+  model: authentik_policies.policybinding

blueprints/system/bootstrap.yaml

@@ -42,9 +42,3 @@ entries:
       user: !KeyOf admin-user
     attrs:
       key: !Context token
-  - model: authentik_blueprints.blueprintinstance
-    identifiers:
-      metadata:
-        labels:
-          blueprints.goauthentik.io/system-bootstrap: "true"
-    state: absent

website/docs/releases/2023/v2023.10.md

@@ -127,6 +127,7 @@ helm upgrade authentik authentik/authentik -f values.yaml --version ^2023.10
 
 ## Fixed in 2023.10.2
 
+-   \*: fix [GHSA-rjvp-29xq-f62w](../security/GHSA-rjvp-29xq-f62w), Reported by [@devSparkle](https://github.com/devSparkle)
 -   blueprints: fix entries with state: absent not being deleted if their serializer has errors (#7345)
 -   crypto: fix race conditions when creating self-signed certificates on startup (#7344)
 -   lifecycle: rework otp_merge migration (#7359)

website/docs/security/GHSA-rjvp-29xq-f62w.md

@@ -0,0 +1,27 @@
+# GHSA-rjvp-29xq-f62w
+
+_Reported by [@devSparkle](https://github.com/devSparkle)_
+
+## Potential Installation takeover when default admin user is deleted
+
+### Summary
+
+In the affected versions, when the default admin user has been deleted, it is potentially possible for an attacker to set the password of the default admin user without any authentication.
+
+### Patches
+
+authentik 2023.8.4 and 2023.10.2 fix this issue, for other versions the workaround can be used.
+
+### Impact
+
+authentik uses a blueprint to create the default admin user, which can also optionally set the default admin users' password from an environment variable. When the user is deleted, the `initial-setup` flow used to configure authentik after the first installation becomes available again.
+
+### Workarounds
+
+Ensure the default admin user (Username `akadmin`) exists and has a password set. It is recommended to use a very strong password for this user, and store it in a secure location like a password manager. It is also possible to deactivate the user to prevent any logins as akadmin.
+
+### For more information
+
+If you have any questions or comments about this advisory:
+
+-   Email us at [security@goauthentik.io](mailto:security@goauthentik.io)

website/sidebars.js

@@ -407,6 +407,7 @@ const docsSidebar = {
             },
             items: [
                 "security/policy",
+                "security/GHSA-rjvp-29xq-f62w",
                 "security/CVE-2023-39522",
                 "security/CVE-2023-36456",
                 "security/2023-06-cure53",