C17PacketCustomPayload — Minecraft 1.8.9 Packet Reference

0x17 C17PacketCustomPayload

Sends a plugin channel message from client to server. Used for mod communication.

Serverbound (Client → Server) · PLAY · net/minecraft/network/play/client/C17PacketCustomPayload.java

pluginmoddingchannel

Fields

Field	Type	Description
channel	String	Plugin channel name (e.g. MC\|BEdit, REGISTER)
data	PacketBuffer (remaining)	Channel-specific payload

Wire Encoding

Field	Type	Notes
Channel	String	Plugin channel identifier
Data Length	short
Data	byte[]	Channel-specific payload

MCP References

MCPNetHandlerPlayServer.processCustomPayload()

Handler Interface

HNDINetHandlerPlayServer

Notes

Common vanilla channels: "MC|BEdit" (book edit), "MC|BSign" (book sign), "MC|ItemName" (anvil rename), "MC|TrSel" (trade select). Mods use their own channel names.

implementation Implementation Cases

BrandChanger (November 0.2 (LunarSpoofer), Gugustus (BLC spoof), Lycoris 2.0 (ServerCrasher), Sigma 3.9)

Spoof client brand on "MC|Brand" channel. ServerCrasher sends crafted payloads on "MC|AdvCdm". Disabler sends fake BLC brand for Badlion Client emulation. Vanilla sends brand, beacon, trading, book, anvil channels.

// Brand spoof
if (event.getPacket() instanceof C17PacketCustomPayload) {
  C17PacketCustomPayload c17 = (C17PacketCustomPayload) event.getPacket();
  if (c17.getChannelName().equals("MC|Brand")) {
    event.setCancelled(true);
    mc.thePlayer.sendQueue.addToSendQueue(new C17PacketCustomPayload("MC|Brand", new PacketBuffer(Unpooled.buffer()).writeString("vanilla")));
  }
}
// Lunar brand spoof
mc.thePlayer.sendQueue.addToSendQueue(new C17PacketCustomPayload("REGISTER", new PacketBuffer(message).writeString("Lunar-Client")));

Vanilla hook: EventSendPacket

Disabler (November 0.2 (LunarSpoofer), Gugustus (BLC spoof), Lycoris 2.0 (ServerCrasher), Sigma 3.9)

/*
 * Decompiled with CFR 0.152.
 * 
 * Could not load the following classes:
 *  com.google.common.eventbus.Subscribe
 *  org.apache.commons.lang3.RandomUtils
 */
package lodomir.dev.modules.impl.exploit;

import com.google.common.eventbus.Subscribe;
import java.util.UUID;
import lodomir.dev.event.impl.EventGetPackets;
import lodomir.dev.event.impl.EventUpdate;
import lodomir.dev.modules.Category;
import lodomir.dev.modules.Module;
import lodomir.dev.settings.ModeSetting;
import lodomir.dev.utils.math.TimeUtils;
import net.minecraft.client.entity.EntityPlayerSP;
import net.minecraft.init.Blocks;
import net.minecraft.item.ItemStack;
import net.minecraft.network.play.client.C00PacketKeepAlive;
import net.minecraft.network.play.client.C02PacketUseEntity;
import net.minecraft.network.play.client.C03PacketPlayer;
import net.minecraft.network.play.client.C08PacketPlayerBlockPlacement;
import net.minecraft.network.play.client.C0APacketAnimation;
import net.minecraft.network.play.client.C0BPacketEntityAction;
import net.minecraft.network.play.client.C0CPacketInput;
import net.minecraft.network.play.client.C0FPacketConfirmTransaction;
import net.minecraft.network.play.client.C18PacketSpectate;
import net.minecraft.network.play.server.S1DPacketEntityEffect;
import net.minecraft.network.play.server.S27PacketExplosion;
import net.minecraft.network.play.server.S2APacketParticles;
import net.minecraft.network.play.server.S44PacketWorldBorder;
import net.minecraft.network.status.client.C01PacketPing;
import net.minecraft.util.BlockPos;
import org.apache.commons.lang3.RandomUtils;

public class Disabler
extends Module {
    public ModeSetting mode = new ModeSetting("Mode", "Basic", "Basic", "Keep Sprint", "Respawn", "Watchdog", "Verus Old", "Verus Combat", "Mineplex Combat", "Kauri", "Hycraft Crash", "Ping", "Test");
    public TimeUtils timer = new TimeUtils();
    public int currentTrans;
    public int count;

    public Disabler() {
        super("Disabler", 0, Category.EXPLOIT);
        this.addSetting(this.mode);
    }

    @Subscribe
    public void onUpdate(EventUpdate event) {
    }

    @Override
    public void onEnable() {
        this.timer.reset();
        super.onEnable();
    }

    @Override
    public void onDisable() {
        super.onDisable();
    }

    @Subscribe
    public void onGetPackets(EventGetPackets p) {
        this.setSuffix(this.mode.getMode());
        switch (this.mode.getMode()) {
            case "Basic": {
                if (!(p.getPackets() instanceof C0FPacketConfirmTransaction) && !(p.getPackets() instanceof C00PacketKeepAlive)) break;
                p.setCancelled(true);
                break;
            }
            case "Mineplex Combat": {
                if (!(p.getPackets() instanceof C00PacketKeepAlive)) break;
                C00PacketKeepAlive c00 = (C00PacketKeepAlive)p.getPackets();
                p.setCancelled(true);
                this.sendPacketSilent(new C00PacketKeepAlive(c00.getKey() - RandomUtils.nextInt((int)1000, (int)Integer.MAX_VALUE)));
                break;
            }
            case "Kauri": {
                if (!(p.getPackets() instanceof C0FPacketConfirmTransaction)) break;
                p.setCancelled(true);
                break;
            }
            case "Watchdog": {
                if (p.getPackets() instanceof C03PacketPlayer) {
                    p.setCancelled(true);
                    break;
                }
            }
            case "Verus Old": {
                this.sendPacketSilent(new C0CPacketInput());
                this.sendPacketSilent(new C18PacketSpectate(UUID.randomUUID()));
                break;
            }
            case "Verus Combat": {
                if (Disabler.mc.thePlayer.ticksExisted <= 20 || Disabler.mc.thePlayer.capabilities.allowFlying || !(p.getPackets() instanceof C0FPacketConfirmTransaction)) break;
                p.setCancelled(true);
                break;
            }
            case "Hycraft Crash": {
                if (!(p.getPackets() instanceof S27PacketExplosion) || !(p.getPackets() instanceof S2APacketParticles) || !(p.getPackets() instanceof S1DPacketEntityEffect) || !(p.getPackets() instanceof S44PacketWorldBorder)) break;
                p.setCancelled(true);
                break;
            }
            case "Ping": {
                if (p.getPackets() instanceof C01PacketPing) {
                    p.setCancelled(true);
                    break;
                }
            }
            case "Respawn": {
                if (Disabler.mc.thePlayer.ticksExisted % 8 != 0 || Disabler.mc.thePlayer.isDead) break;
                Disabler.mc.thePlayer.fall(20.0f, 1.0f);
                this.sendPacket(new C08PacketPlayerBlockPlacement(new BlockPos(Disabler.mc.thePlayer.posX, Disabler.mc.thePlayer.posY + 1.5, Disabler.mc.thePlayer.posZ), 1, new ItemStack(Blocks.stone.getItem(Disabler.mc.theWorld, new BlockPos(-1, -1, -1))), 0.0f, 0.94f, 0.0f));
                this.sendPacket(new C03PacketPlayer.C04PacketPlayerPosition(Disabler.mc.thePlayer.posX, Disabler.mc.thePlayer.posY + 20.0, Disabler.mc.thePlayer.posZ, false));
                this.sendPacket(new C03PacketPlayer.C04PacketPlayerPosition(Disabler.mc.thePlayer.posX, Disabler.mc.thePlayer.posY, Disabler.mc.thePlayer.posZ, false));
                this.sendPacket(new C03PacketPlayer.C04PacketPlayerPosition(Disabler.mc.thePlayer.posX, Disabler.mc.thePlayer.posY + (double)0.42f, Disabler.mc.thePlayer.posZ, true));
                break;
            }
            case "Test": {
                if (!(p.getPackets() instanceof C03PacketPlayer) || !(p.getPackets() instanceof C0FPacketConfirmTransaction)) break;
                if (this.timer.hasReached(1000L) && Disabler.mc.thePlayer.ticksExisted % 8 == 0) {
                    if (p.getPackets() instanceof C03PacketPlayer.C04PacketPlayerPosition || p.getPackets() instanceof C03PacketPlayer.C06PacketPlayerPosLook || p.getPackets() instanceof C08PacketPlayerBlockPlacement || p.getPackets() instanceof C0APacketAnimation || p.getPackets() instanceof C0BPacketEntityAction || p.getPackets() instanceof C02PacketUseEntity) {
                        this.sendPacketSilent(new C03PacketPlayer.C04PacketPlayerPosition(Disabler.mc.thePlayer.prevPosX, Disabler.mc.thePlayer.prevPosY, Disabler.mc.thePlayer.prevPosZ, true));
                    }
                    p.setCancelled(true);
                }
                if (p.getPackets() instanceof C01PacketPing && this.timer.hasReached(4000L)) {
                    p.setCancelled(true);
                }
                this.timer.reset();
                break;
            }
            case "Keep Sprint": {
                if (!(p.getPackets() instanceof C0BPacketEntityAction)) break;
                C0BPacketEntityAction c0B = (C0BPacketEntityAction)p.getPackets();
                if (c0B.getAction().equals((Object)C0BPacketEntityAction.Action.START_SPRINTING)) {
                    if (EntityPlayerSP.serverSprintState) {
                        this.sendPacketSilent(new C0BPacketEntityAction(Disabler.mc.thePlayer, C0BPacketEntityAction.Action.STOP_SPRINTING));
                        EntityPlayerSP.serverSprintState = false;
                    }
                    p.setCancelled(true);
                }
                if (!c0B.getAction().equals((Object)C0BPacketEntityAction.Action.STOP_SPRINTING)) break;
                p.setCancelled(true);
            }
        }
    }
}

Vanilla hook: EventSendPacket

ServerCrasher (November 0.2 (LunarSpoofer), Gugustus (BLC spoof), Lycoris 2.0 (ServerCrasher), Sigma 3.9)

// Brand spoof
if (event.getPacket() instanceof C17PacketCustomPayload) {
  C17PacketCustomPayload c17 = (C17PacketCustomPayload) event.getPacket();
  if (c17.getChannelName().equals("MC|Brand")) {
    event.setCancelled(true);
    mc.thePlayer.sendQueue.addToSendQueue(new C17PacketCustomPayload("MC|Brand", new PacketBuffer(Unpooled.buffer()).writeString("vanilla")));
  }
}
// Lunar brand spoof
mc.thePlayer.sendQueue.addToSendQueue(new C17PacketCustomPayload("REGISTER", new PacketBuffer(message).writeString("Lunar-Client")));

Vanilla hook: EventSendPacket

LunarSpoofer (November 0.2 (LunarSpoofer), Gugustus (BLC spoof), Lycoris 2.0 (ServerCrasher), Sigma 3.9)

// Brand spoof
if (event.getPacket() instanceof C17PacketCustomPayload) {
  C17PacketCustomPayload c17 = (C17PacketCustomPayload) event.getPacket();
  if (c17.getChannelName().equals("MC|Brand")) {
    event.setCancelled(true);
    mc.thePlayer.sendQueue.addToSendQueue(new C17PacketCustomPayload("MC|Brand", new PacketBuffer(Unpooled.buffer()).writeString("vanilla")));
  }
}
// Lunar brand spoof
mc.thePlayer.sendQueue.addToSendQueue(new C17PacketCustomPayload("REGISTER", new PacketBuffer(message).writeString("Lunar-Client")));

Vanilla hook: EventSendPacket

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