Unnecessary Data Transmission in Server-Client Communication

[Gylesie]

Introduction to the Security Issue

I have identified a significant security issue within the server's data transmission process to client browsers, especially concerning the widget functionalities. This issue arises from transmitting excess data beyond what is necessary, posing potential security risks. Importantly, these risks are relevant not only in scenarios where the homepage is accessible over the web but also in local environments. While localhost attacks may be less prevalent, they are feasible and could exploit such vulnerabilities. Therefore, it's crucial to address this excessive data transmission to mitigate security risks in all usage contexts.

Specific Example: Portainer Widget

For instance, in the Portainer widget, the requirement is to display counts of running, stopped, and total containers. However, the data sent from the server includes extensive details about each container, such as IDs, labels, mountpoints, and published ports. This goes beyond what's needed for the widget's functionality and inadvertently increases the risk of unnecessary data exposure on a local network.

Security Implications

• Risk of Local Network Exposure: Sending extensive, unneeded data could inadvertently expose sensitive information within a local network, making it susceptible to potential vulnerabilities.
• Potential for Unintended Access: The surplus data, especially when using the software in shared or semi-public local network environments, increases the risk of unintended access or misuse.
• General Security Best Practices: Minimizing data transmission aligns with broader security best practices, ensuring that only essential data is communicated, thus reducing the exposure footprint.

Proposed Solution

I suggest implementing a data filtering mechanism at the server level, which would ensure that only the data necessary for each widget’s display is sent to the client.

Anticipated Impact

By adopting this solution, I anticipate a significant improvement in the security posture of the system by minimizing data exposure. It will also lead to more efficient bandwidth usage.

Steps to reproduce

N/A

homepage version

v0.8.3

Installation method

Docker

Configuration

No response

Container Logs

No response

Browser Logs

No response

Troubleshooting

N/A

Other

No response

Before submitting, I have made sure to

• Check the documentation
• Follow the troubleshooting guide (please include output above if applicable).
• Search existing issues and discussions.

[shamoon]

Per your example, portainer, the same data is transmitted by accessing portainer via the web, this is literally no different. All data is transmitted proxied, meaning from the source API to the homepage server securely (though specifics depend a little on setup), from there it is up to the user how to serve the client. If the client is being accessed via https, which is pretty standard these days for serving things publicly, all traffic is encrypted. I dont see this as a vulnerability.

That said, the idea of filtering out data to improve things is fine with me as a 'feature request'.

[Gylesie]

Thank you for your insights regarding the secure proxying of data from the source API to the server and the encryption of client traffic.

However, I would like to point out that while MITM attacks are mitigated through these measures, there are other potential security vulnerabilities that need consideration. There's a concern when the homepage is exposed to people that are not authorized to access some of the services that are present as widgets on the homepage. Then anyone could potentially view more information than they're authorized to see. While homepage widgets typically display only basic information, which is generally acceptable even for unauthorized people, accessing more detailed data requires a login or an API key to respective services. However, the proxy transmits this information to EVERY client, creating a situation where possibly unauthorized users might gain access to sensitive data.

Lets assume another, more comprehensive example:
We have openly accessible homepage instance on some (LAN or other) network. Everyone can access the homepage and therefore the data of the widgets. Let one of the widgets be a Qbittorrent widget. Then any user, even such that cannot access the qbittorrent instance, because they do not know the credentials for qbittorrent, is able to get the full list of all torrents present together with lists of trackers for each torrent that often include sensitive data such as passkeys, etc. This user would be able to facilicate the data in harmful way.

Even if the user is not nefarious, the network or even clients can be breached by 3rd party that will be able to carry out such attack. I hope you can see my point more clearly. Feel free to ask for any further clarification.

[shamoon]

This is a manufactured example, so I can manufacture a solution: dont share homepage with people you dont trust. Again, Im not suggesting it would be a bad thing to filter out extra data but I dont see how this is anything other than the responsibility of the host. You literally need to use credentials to access lots of the data (like your portainer key), so by definition homepage is using 'privileged' data, that would seem inherently obvious to anyone deploying it...

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