Fixing Bug API Key Sharing Between WebIDs In Moviestar

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Introduction

This document details a critical bug discovered in the moviestar application, where API keys configured for one WebID are incorrectly being written to the POD (Personal Online Data) of another WebID. This issue poses a significant security risk, as it could potentially allow unauthorized access to user data and services. The following sections provide a comprehensive overview of the bug, including the steps to reproduce it, the expected behavior, and proposed solutions.

Discussion Category

anusii, moviestar

Additional Information

Context: https://github.com/anusii/moviestar/pull/98#pullrequestreview-3036801890 @cdawei

Bug Description

When switching between different WebIDs within the moviestar application, a critical bug has been identified where the API key associated with one WebID (webID1) is automatically and incorrectly written to the Personal Online Data (POD) of another WebID (webID2). This behavior leads to a significant security vulnerability, as it effectively shares API keys across different user accounts. This issue arises because the application does not properly isolate API key storage per WebID, leading to potential data breaches and unauthorized access.

The core of the problem lies in how the application manages and stores API keys. Instead of maintaining separate storage for each WebID, it appears the application is either using a global storage location or failing to properly segregate keys based on the active WebID. This means that when a user logs in with a new WebID, the application mistakenly overwrites or shares the previously configured API key, leading to the observed behavior. This bug is particularly concerning as it violates the principle of least privilege and could allow malicious actors to gain unauthorized access to sensitive user data.

The implications of this bug are far-reaching. If an attacker were to gain access to a single compromised WebID, they could potentially leverage the shared API key to access data associated with other WebIDs. This could lead to data theft, service disruption, and other severe consequences. Therefore, addressing this bug is of paramount importance to ensure the security and privacy of moviestar users.

Steps to Reproduce

To replicate this bug and verify its existence, follow these precise steps:

  1. Set up webID1 with an API key: Initially, configure the moviestar application with an API key for a specific WebID, which we'll refer to as webID1. This involves entering the API key into the application's settings or configuration panel while logged in as webID1. Ensure that the API key is correctly associated with webID1 and stored within the application's storage mechanisms.
  2. Create a new webID2: Next, create a completely new WebID, which we'll call webID2. This WebID should not have any prior association with the moviestar application or any configured API keys. The purpose of this step is to simulate a new user logging into the application for the first time.
  3. Log into moviestar using webID2: Log out of webID1 within the moviestar application and then log in using the newly created webID2. This action simulates a user switching between different accounts within the application.
  4. Observe the API key in webID2's POD: After logging in with webID2, navigate to the POD (Personal Online Data) storage location associated with webID2. Specifically, examine the API key .ttl file within webID2's POD. You will observe that the API key that was initially configured for webID1 has been automatically written to this file. This confirms the bug where API keys are being incorrectly shared between WebIDs.

By following these steps, you can consistently reproduce the bug and verify the incorrect behavior of the application. This process is crucial for understanding the scope of the issue and ensuring that any proposed solutions effectively address the root cause.

Expected Behavior

The expected behavior of the moviestar application, in terms of API key management, should adhere to the following principles to ensure security and user privacy:

  • Each WebID should have its own isolated API key configuration: This is the fundamental principle. Each WebID should maintain its own unique set of API keys, independent of other WebIDs. This isolation prevents unauthorized access and ensures that actions performed under one WebID are not attributed to another.
  • API keys should not be shared between different WebIDs: This is a direct consequence of the first point. The application should never copy, transfer, or otherwise share API keys across different WebIDs. Sharing API keys creates a significant security vulnerability, as a compromise of one WebID could lead to the compromise of others.
  • When logging in with a new WebID, the app should either:
    • Request the user to set up their own API key: This is the preferred approach for enhanced security. When a user logs in with a new WebID, the application should prompt them to configure their API key specifically for that WebID. This ensures that the user is aware of the key's purpose and scope.
    • Only use an existing API key if it was specifically set for that WebID: If the application needs to use an existing API key, it should only do so if the key was explicitly configured for the currently logged-in WebID. This prevents the accidental or malicious use of API keys associated with other accounts.

These expected behaviors are crucial for maintaining the integrity and security of user data within the moviestar application. Deviations from these principles, such as the observed bug, can lead to serious security breaches and compromise user privacy.

Proposed Solution

To address the identified bug and ensure proper API key isolation within the moviestar application, several solutions can be implemented. These solutions focus on isolating API key storage per WebID, thereby preventing the accidental or malicious sharing of keys. Here are some proposed solutions:

  1. Store API keys in the POD instead of local device storage:

    • Explanation: Currently, the application may be storing API keys in the local storage of the user's device. This approach makes it difficult to isolate keys per WebID, as the local storage is accessible to the application regardless of the active WebID. Storing API keys within the POD, which is a user-controlled online data store, allows for better isolation. Each WebID has its own POD, so storing the API key within the POD ensures that it is only accessible when that WebID is logged in.
    • Implementation: Modify the application to store and retrieve API keys from the user's POD. This involves using Solid's data management APIs to write and read the API key from a specific location within the POD. Ensure that the location is secured and only accessible to the WebID owner.

  2. Use WebID-specific keys in local storage (e.g., api_key_{webId_hash}):

    • Explanation: If storing API keys in local storage is necessary for performance or other reasons, the application can use WebID-specific keys to differentiate between API keys for different WebIDs. This involves creating a unique key for each WebID by incorporating a hash or other unique identifier of the WebID into the key name.
    • Implementation: When storing an API key, generate a unique key name by hashing the WebID (e.g., using SHA-256) and appending it to a base key name (e.g., api_key_). When retrieving an API key, use the same hashing algorithm to generate the key name based on the current WebID.

  3. Clear local API key storage when switching WebIDs:

    • Explanation: Another approach is to clear the local API key storage whenever a user switches WebIDs. This ensures that no API key from a previous WebID remains in storage when a new WebID is logged in.
    • Implementation: Implement a mechanism that clears the local storage location where API keys are stored whenever the user logs out or switches to a different WebID. This can be done by deleting the API key file or removing the corresponding entry from the local storage.

  4. Prompt users to enter API key for each new WebID:

    • Explanation: For enhanced security and user awareness, the application can prompt users to enter their API key whenever they log in with a new WebID. This ensures that the user is explicitly setting the API key for each WebID and prevents the accidental use of keys from other accounts.
    • Implementation: Modify the login process to include a step where the user is prompted to enter their API key. This prompt should only appear when the user logs in with a WebID for the first time or when the API key is not found for the current WebID.

These solutions offer different approaches to address the API key sharing bug. The optimal solution may depend on the specific requirements and constraints of the moviestar application. However, implementing one or more of these solutions will significantly improve the security and privacy of user data.

Conclusion

The bug identified in the moviestar application, where API keys are incorrectly shared between WebIDs, poses a significant security risk. The steps to reproduce this bug are straightforward, and the expected behavior clearly dictates that API keys should be isolated per WebID. The proposed solutions, ranging from storing API keys in the POD to prompting users for their API key upon each new WebID login, offer various avenues to rectify this issue. Addressing this bug is crucial to ensure the security and privacy of moviestar users and maintain the integrity of the application.