CustomPayloadFixer (BungeeCord & Bukkit/Spigot)

Requires ProtocolLib (if you're going to use this plugin on Bukkit/Spigot servers).

Recently, a huge exploit was found with PacketPlayInCustomPayload (this packet is being used for plugin messages and "chatting" between Minecraft client and server (requesting to open a trade with villager, telling the server that client has picked up the item, etc.).

People with hacked clients could send tons of packets requesting to change book's meta (channels MC|BSign, MC|BEdit, REGISTER), which caused server to overload and crash.

This plugin fixes this issue by limiting the amount of packets being sent on these channels (once per 100 milliseconds) and checking for corrupted NBT tags (works only on Bukkit/Spigot servers).

You can change what you want to do with the exploiter: dispatch a fancy /ban command (use the %name% placeholder to specify exploiters nickname in 'dispatchCommand' field in the configuration file) or kick him with a glorious message, all can be changed within the configuration file.

Note: this plugin only supports Spigot/CraftBukkit on Minecraft versions from 1.8 to the latest versions of 1.11, newer versions do not require this plugin, since the bug has been internally fixed by the Spigot Team.