GHSA-6hjj-gq77-j4qw Label Studio Object Relational Mapper Leak Vulnerability in Filtering Task

• PyPI label-studio: < 1.9.2.post0 → fixed in 1.9.2.post0

Introduction This write-up describes a vulnerability found in Label Studio, a popular open source data labeling tool. The vulnerability affects all versions of Label Studio prior to `1.9.2post0` and was tested on version `1.8.2`. Overview In all current versions of Label Studio, the application allows users to insecurely set filters for filtering tasks. An attacker can construct a *filter chain* to filter tasks based on sensitive fields for all user accounts on the platform by exploiting Django's Object Relational Mapper (ORM). Since the results of query can be manipulated by the ORM filter, an attacker can leak these sensitive fields character by character. For an example, the following filter chain will task results by the password hash of an account on Label Studio. ``` filter:tasks:updated_by__active_organization__active_users__password ``` For consistency, this type of vulnerability will be termed as ORM Leak in the rest of this disclosure. In addition, Label Studio had a hard coded secret key that an attacker can use to forge a session token of any user by exploiting this ORM Leak vulnerability to leak account password hashes. Description The following code snippet from the `ViewSetSerializer` in `label_studio/data_manager/serializers.py` insecurely creates `Filter` objects from a JSON `POST` request to the `/api/dm/views/{viewId}` API endpoint. ```python @staticmethod def _create_filters(filter_group, filters_data): filter_index = 0 for filter_data in filters_data: filter_data["index"] = filter_index filter_group.filters.add(Filter.objects.create(filter_data)) filter_index += 1 ``` These `Filter` objects are then applied in the `TaskQuerySet` in `label_studio/data_manager/managers.py`. ```python class TaskQuerySet(models.QuerySet): def prepared(self, prepare_params=None): """ Apply filters, ordering and selected items to queryset :param prepare_params: prepare params with project, filters, orderings, etc :return: ordered and filtered queryset """ from projects.models import Project queryset = self if prepare_params is None: return queryset project = Project.objects.get(pk=prepare_params.project) request = prepare_params.request queryset = apply_filters(queryset, prepare_params.filters, project, request) queryset = apply_ordering(queryset, prepare_params.ordering, project, request, view_data=prepare_params.data) if not prepare_params.selectedItems: return queryset # included selected items if prepare_params.selectedItems.all is False and prepare_params.selectedItems.included: queryset = queryset.filter(id__in=prepare_params.selectedItems.included) # excluded selected items elif prepare_params.selectedItems.all is True and prepare_params.selectedItems.excluded: queryset = queryset.exclude(id__in=prepare_params.selectedItems.excluded) return queryset ``` 1. User provided filters are insecurely applied here by calling the `apply_filters` that constructs the Django ORM filter. The `PreparedTaskManager` in `label_studio/data_manager/managers.py` uses the vulnerable `TaskQuerySet` for building the Django queryset for querying `Task` objects, as shown in the following code snippet. ```python class PreparedTaskManager(models.Manager): #... def get_queryset(self, fields_for_evaluation=None, prepare_params=None, all_fields=False): """ :param fields_for_evaluation: list of annotated fields in task :param prepare_params: filters, ordering, selected items :param all_fields: evaluate all fields for task :param request: request for user extraction :return: task queryset with annotated fields """ queryset = self.only_filtered(prepare_params=prepare_params) return self.annotate_queryset( queryset, fields_for_evaluation=fields_for_evaluation, all_fields=all_fields, request=prepare_params.request ) def only_filtered(self, prepare_params=None): request = prepare_params.request queryset = TaskQuerySet(self.model).filter(project=prepare_params.project) fields_for_filter_ordering = get_fields_for_filter_ordering(prepare_params) queryset = self.annotate_queryset(queryset, fields_for_evaluation=fields_for_filter_ordering, request=request) return queryset.prepared(prepare_params=prepare_params) ``` 1. Special Django method for the `models.Manager` class that is used to retrieve the queryset for querying objects of a model. 2. Uses the vulnerable `TaskQuerySet` that was explained above. The following code snippet of the `Task` model in `label_studio/tasks/models.py` shows that the vulnerable `PreparedTaskManager` is set as a class variable, along with the `updated_by` relational mapping to a Django user that will be exploited as the entrypoint of the filter chain. ```python ... class Task(TaskMixin, models.Model): """ Business tasks from project """ id = models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID', db_index=True) # ... updated_by = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='updated_tasks', on_delete=models.SET_NULL, null=True, verbose_name=_('updated by'), help_text='Last annotator or reviewer who updated this task') # ... objects = TaskManager() # task manager by default prepared = PreparedTaskManager() # task manager with filters, ordering, etc for data_manager app # ... ``` 1. The entry point of the filter chain to filter by the `updated_by__active_organization__active_users__password`. 2. The vulnerable `PreparedTaskManager` being set that will be exploited. Finally, the `TaskListAPI` view set in `label_studio/tasks/api.py` with the `/api/tasks` API endpoint uses the vulnerable `PreparedTaskManager` to filter `Task` objects. ```python def get_queryset(self): task_id = self.request.parser_context['kwargs'].get('pk') task = generics.get_object_or_404(Task, pk=task_id) review = bool_from_request(self.request.GET, 'review', False) selected = {"all": False, "included": [self.kwargs.get("pk")]} if review: kwargs = { 'fields_for_evaluation': ['annotators', 'reviewed'] } else: kwargs = {'all_fields': True} project = self.request.query_params.get('project') or self.request.data.get('project') if not project: project = task.project.id return self.prefetch( Task.prepared.get_queryset( prepare_params=PrepareParams(project=project, selectedItems=selected, request=self.request), kwargs )) ``` 1. Uses the vulnerable `PreparedTaskManager` to filter objects. Proof of Concept Below are the steps to exploit about how to exploit this vulnerability to leak the password hash of an account on Label Studio. 1. Create two accounts on Label Studio and choose one account to be the victim and the other the hacker account that you will use. 2. Create a new project or use an existing project, then add a task to the project. …