security: fix CVE-2024-42490 (cherry-pick #11022) (#11024)

security: fix CVE-2024-42490 (#11022)

CVE-2024-42490

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

authentik/core/api/used_by.py

@@ -14,6 +14,7 @@ from rest_framework.request import Request
 from rest_framework.response import Response
 
 from authentik.core.api.utils import PassiveSerializer
+from authentik.rbac.filters import ObjectFilter
 
 
 class DeleteAction(Enum):
@@ -53,7 +54,7 @@ class UsedByMixin:
     @extend_schema(
         responses={200: UsedBySerializer(many=True)},
     )
-    @action(detail=True, pagination_class=None, filter_backends=[])
+    @action(detail=True, pagination_class=None, filter_backends=[ObjectFilter])
     def used_by(self, request: Request, *args, **kwargs) -> Response:
         """Get a list of all objects that use this object"""
         model: Model = self.get_object()

authentik/crypto/api.py

@@ -36,6 +36,7 @@ from authentik.crypto.builder import CertificateBuilder, PrivateKeyAlg
 from authentik.crypto.models import CertificateKeyPair
 from authentik.events.models import Event, EventAction
 from authentik.rbac.decorators import permission_required
+from authentik.rbac.filters import ObjectFilter
 
 LOGGER = get_logger()
 
@@ -266,7 +267,7 @@ class CertificateKeyPairViewSet(UsedByMixin, ModelViewSet):
         ],
         responses={200: CertificateDataSerializer(many=False)},
     )
-    @action(detail=True, pagination_class=None, filter_backends=[])
+    @action(detail=True, pagination_class=None, filter_backends=[ObjectFilter])
     def view_certificate(self, request: Request, pk: str) -> Response:
         """Return certificate-key pairs certificate and log access"""
         certificate: CertificateKeyPair = self.get_object()
@@ -296,7 +297,7 @@ class CertificateKeyPairViewSet(UsedByMixin, ModelViewSet):
         ],
         responses={200: CertificateDataSerializer(many=False)},
     )
-    @action(detail=True, pagination_class=None, filter_backends=[])
+    @action(detail=True, pagination_class=None, filter_backends=[ObjectFilter])
     def view_private_key(self, request: Request, pk: str) -> Response:
         """Return certificate-key pairs private key and log access"""
         certificate: CertificateKeyPair = self.get_object()

authentik/crypto/tests.py

@@ -214,6 +214,46 @@ class TestCrypto(APITestCase):
         self.assertEqual(200, response.status_code)
         self.assertIn("Content-Disposition", response)
 
+    def test_certificate_download_denied(self):
+        """Test certificate export (download)"""
+        self.client.logout()
+        keypair = create_test_cert()
+        response = self.client.get(
+            reverse(
+                "authentik_api:certificatekeypair-view-certificate",
+                kwargs={"pk": keypair.pk},
+            )
+        )
+        self.assertEqual(403, response.status_code)
+        response = self.client.get(
+            reverse(
+                "authentik_api:certificatekeypair-view-certificate",
+                kwargs={"pk": keypair.pk},
+            ),
+            data={"download": True},
+        )
+        self.assertEqual(403, response.status_code)
+
+    def test_private_key_download_denied(self):
+        """Test private_key export (download)"""
+        self.client.logout()
+        keypair = create_test_cert()
+        response = self.client.get(
+            reverse(
+                "authentik_api:certificatekeypair-view-private-key",
+                kwargs={"pk": keypair.pk},
+            )
+        )
+        self.assertEqual(403, response.status_code)
+        response = self.client.get(
+            reverse(
+                "authentik_api:certificatekeypair-view-private-key",
+                kwargs={"pk": keypair.pk},
+            ),
+            data={"download": True},
+        )
+        self.assertEqual(403, response.status_code)
+
     def test_used_by(self):
         """Test used_by endpoint"""
         self.client.force_login(create_test_admin_user())
@@ -246,6 +286,26 @@ class TestCrypto(APITestCase):
             ],
         )
 
+    def test_used_by_denied(self):
+        """Test used_by endpoint"""
+        self.client.logout()
+        keypair = create_test_cert()
+        OAuth2Provider.objects.create(
+            name=generate_id(),
+            client_id="test",
+            client_secret=generate_key(),
+            authorization_flow=create_test_flow(),
+            redirect_uris="http://localhost",
+            signing_key=keypair,
+        )
+        response = self.client.get(
+            reverse(
+                "authentik_api:certificatekeypair-used-by",
+                kwargs={"pk": keypair.pk},
+            )
+        )
+        self.assertEqual(403, response.status_code)
+
     def test_discovery(self):
         """Test certificate discovery"""
         name = generate_id()

authentik/flows/api/flows.py

@@ -33,6 +33,7 @@ from authentik.lib.utils.file import (
 )
 from authentik.lib.views import bad_request_message
 from authentik.rbac.decorators import permission_required
+from authentik.rbac.filters import ObjectFilter
 
 LOGGER = get_logger()
 
@@ -277,7 +278,7 @@ class FlowViewSet(UsedByMixin, ModelViewSet):
             400: OpenApiResponse(description="Flow not applicable"),
         },
     )
-    @action(detail=True, pagination_class=None, filter_backends=[])
+    @action(detail=True, pagination_class=None, filter_backends=[ObjectFilter])
     def execute(self, request: Request, slug: str):
         """Execute flow for current user"""
         # Because we pre-plan the flow here, and not in the planner, we need to manually clear

authentik/outposts/api/service_connections.py

@@ -23,6 +23,7 @@ from authentik.outposts.models import (
     KubernetesServiceConnection,
     OutpostServiceConnection,
 )
+from authentik.rbac.filters import ObjectFilter
 
 
 class ServiceConnectionSerializer(ModelSerializer, MetaNameSerializer):
@@ -88,7 +89,7 @@ class ServiceConnectionViewSet(
         return Response(TypeCreateSerializer(data, many=True).data)
 
     @extend_schema(responses={200: ServiceConnectionStateSerializer(many=False)})
-    @action(detail=True, pagination_class=None, filter_backends=[])
+    @action(detail=True, pagination_class=None, filter_backends=[ObjectFilter])
     def state(self, request: Request, pk: str) -> Response:
         """Get the service connection's state"""
         connection = self.get_object()

website/docs/security/CVE-2024-42490.md

@@ -0,0 +1,31 @@
+# CVE-2024-42490
+
+_Reported by [@m2a2](https://github.com/m2a2)_
+
+## Improper Authorization for Token modification
+
+### Summary
+
+Several API endpoints can be accessed by users without correct authentication/authorization.
+
+The main API endpoints affected by this:
+
+-   `/api/v3/crypto/certificatekeypairs/<uuid>/view_certificate/`
+-   `/api/v3/crypto/certificatekeypairs/<uuid>/view_private_key/`
+-   `/api/v3/.../used_by/`
+
+Note that all of the affected API endpoints require the knowledge of the ID of an object, which especially for certificates is not accessible to an unprivileged user. Additionally the IDs for most objects are UUIDv4, meaning they are not easily guessable/enumerable.
+
+### Patches
+
+authentik 2024.4.4, 2024.6.4 and 2024.8.0 fix this issue.
+
+### Workarounds
+
+Access to the API endpoints can be blocked at a Reverse-proxy/Load balancer level to prevent this issue from being exploited.
+
+### 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

@@ -436,6 +436,7 @@ const docsSidebar = {
             },
             items: [
                 "security/policy",
+                "security/CVE-2024-42490",
                 "security/CVE-2024-38371",
                 "security/CVE-2024-37905",
                 "security/CVE-2024-23647",