Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.6.0-alpha.35 and 8.6.50, when a Parse.Cloud.afterLiveQueryEvent trigger is registered for a class, the LiveQuery server leaks protected fields and authData to all subscribers of that class. Fields configured as protected via Class-Level Permissions (protectedFields) are included in LiveQuery event payloads for all event types (create, update, delete, enter, leave). Any user with sufficient CLP permissions to subscribe to the affected class can receive protected field data of other users, including sensitive personal information and OAuth tokens from third-party authentication providers. The vulnerability was caused by a reference detachment bug. When an afterEvent trigger is registered, the LiveQuery server converts the event object to a Parse.Object for the trigger, then creates a new JSON copy via toJSONwithObjects(). The sensitive data filter was applied to the Parse.Object reference, but the unfiltered JSON copy was sent to clients. The fix in versions 9.6.0-alpha.35 and 8.6.50 ensures that the JSON copy is assigned back to the response object before filtering, so the filter operates on the actual data sent to clients. As a workaround, remove all Parse.Cloud.afterLiveQueryEvent trigger registrations. Without an afterEvent trigger, the reference detachment does not occur and protected fields are correctly filtered.
Weakness
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
Extended Description
There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker. Some kinds of sensitive information include:
Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected. These parties include:
Information exposures can occur in different ways:
It is common practice to describe any loss of confidentiality as an “information exposure,” but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read. CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.
Potential Mitigations
- Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
- Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Related Attack Patterns
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