From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: NONPLAYT <76615486+NONPLAYT@users.noreply.github.com>
Date: Thu, 23 May 2024 02:06:30 +0300
Subject: [PATCH] Block Log4Shell exploit


diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index 9ae16e24013ea5664d4ea6d52ed7dd188404890f..59d26f63fd6b6df86ae357be3fd530c1b9eb4394 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -2455,6 +2455,7 @@ public class ServerGamePacketListenerImpl extends ServerCommonPacketListenerImpl
     }
 
     private void tryHandleChat(String s, Runnable runnable, boolean sync) { // CraftBukkit
+        if (ServerGamePacketListenerImpl.isLog4ShellExploit(s)) return; // DivineMC - Block Log4Shell exploit
         if (ServerGamePacketListenerImpl.isChatMessageIllegal(s)) {
             this.disconnectAsync((Component) Component.translatable("multiplayer.disconnect.illegal_characters"), org.bukkit.event.player.PlayerKickEvent.Cause.ILLEGAL_CHARACTERS); // Paper // Paper - add proper async disconnect
         } else if (this.player.isRemoved() || this.player.getChatVisibility() == ChatVisiblity.HIDDEN) { // CraftBukkit - dead men tell no tales
@@ -2486,6 +2487,15 @@ public class ServerGamePacketListenerImpl extends ServerCommonPacketListenerImpl
         }
     }
 
+    // DivineMC start - Block Log4Shell exploit
+    public static boolean isLog4ShellExploit(String message) {
+        java.util.regex.Pattern pattern = java.util.regex.Pattern.compile(".*\\$\\{[^}]*}.*");
+        java.util.regex.Matcher matcher = pattern.matcher(message);
+
+        return matcher.find();
+    }
+    // DivineMC end
+
     public static boolean isChatMessageIllegal(String message) {
         for (int i = 0; i < message.length(); ++i) {
             if (!StringUtil.isAllowedChatCharacter(message.charAt(i))) {
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index 63065a22ff359c142bab23fccacfd5ebd86f81a5..ab257415665d80a1fc7d877831fc74ad50a6790a 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -758,6 +758,8 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         Preconditions.checkArgument(msg != null, "msg cannot be null");
 
         if (this.getHandle().connection == null) return;
+        
+        if (ServerGamePacketListenerImpl.isLog4ShellExploit(msg)) return; // DivineMC - Block Log4Shell exploit
 
         // Paper start - Improve chat handling
         if (ServerGamePacketListenerImpl.isChatMessageIllegal(msg)) {