Mod Detection Preventer

⚠️ For now please stop using this mod. Another method of detecting mods has been found, and I am not able to resolve it at this time. Using this mod might cause you to get banned. ⚠️

A simple mod that prevents a security vulnerability allowing servers to detect which mods are installed on the client side.

While I try my best to keep this mod up to date, server admins might find a new method to access your mods-list. It is always recommended that you follow the server rules.

The Vulnerability

Minecraft has a feature that allows text (in chat, on signs, or in the bossbar) to be specified by a keybind the user has set, or a translation key. The Client will then replace the translation key, or the keybind with the stored value. This can be abused by the server by serving the client a sign with such a placeholder (for example Sodium: sodium.option_impact.low). By immediately closing the sign screen, the client sends the edited text to the server without ever seeing a sign open screen. The server can then detect wether you have that specific mod installed, by checking if your client replaced the placeholder with the corresponding text (sodium.option_impact.low -> Low). If you don't have Sodium installed, the placeholder will stay there (sodium.option_impact.low -> sodium.option_impact.low).

This also works on the Anvil screen. The server could prompt you to open the anvil screen, with an item in the renaming slot that has a translation key as it's name. The client would then rename the item to the corresponding value and send an update to the server. (Huge thanks to Frog, @croaak on discord, for figuring this out)

This detection method works for any mod that has custom translations.

The Fix

This mod fixes this issue by simply not resolving any translation or keybind placeholders on signs, except vanilla ones. This makes it impossible for the server to use this method to detect installed mods.

To verify this works you can test it in a test world.