BookExploitFix 0.15

Native Minecraft Version:

1.15

Tested Minecraft Versions:

• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15

This plugin aims to fix an exploit on recent Spigot/CraftBukkit servers which allows players to create books which execute commands on click.

Does my server need this plugin?
Your server is vulnerable to this exploit when ONE of these conditions are met:
Your server version is between 1.8 and 1.8.3
OR
Your server version is 1.8 or newer (including 1.9, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15) and players have creative mode

How does it work?
Since version 1.8, book pages are stored as JSON strings, which allow to encode actions when the text is clicked. This includes opening URL, executing commands, etc. Hackers exploit this by encoding commands like /op and then try to get someone with the appropriate permissions to click the page. In less drastic cases, they can use it to get unsuspecting players to transfer money, give build permissions, etc.

What does the plugin do?
This plugin counters these atempts by filtering the book pages on certain ingame events and replacing the potentially harmful actions with a simple and harmless hover message.


Plugin Description

Commands:

/filter - Actively applies the filter on the book in your hand.
aliases: /bookfilter | /filterbook

Permissions:

bookfilter.filter - Gives access to the /filter command
bookfilter.overridefilter - Overrides filtering when reading books

Requirements:

CraftBukkit or Spigot version 1.8 - 1.15
Java 8 or newer

I recommend to "Watch This Resource" as I will push critical fixes as fast as I can. Any feedback and suggestions for improvement are very welcome!

History
Spigot has fixed the exploit for survival mode in this commit which means in spitogt/craftbukkit version 1.8.3 and later. In creative mode, inventories are handled differently and is therefore still affected.

Disclaimer: I have testet this plugin in test and live environments. However, plugins can always contain bugs and unintended behaviour. If you use this plugin, you do so on your own risk. I cannot be held responsible for any consequences from using this plugin. If you encounter any bugs, please report them so they can be fixed.