diff --git a/build.gradle b/build.gradle
index 652d5ce..24f5918 100644
--- a/build.gradle
+++ b/build.gradle
@@ -55,6 +55,7 @@ minecraft {
 }
 
 repositories {
+    mavenCentral()
     maven {
         name 'spigot-repo'
         url 'https://hub.spigotmc.org/nexus/content/repositories/public/'
@@ -64,6 +65,16 @@ repositories {
 dependencies {
     minecraft 'net.minecraftforge:forge:1.12.2-14.23.5.2855'
     implementation 'org.spigotmc:spigot-api:1.16.5-R0.1-SNAPSHOT'
+
+    testImplementation('org.junit:junit-bom:5.8.2')
+    testImplementation('org.junit.jupiter:junit-jupiter:5.8.2')
+}
+
+test {
+    useJUnitPlatform()
+    testLogging {
+        events "passed", "skipped", "failed"
+    }
 }
 
 // Example for how to get properties into the manifest for reading by the runtime..
diff --git a/src/main/java/chloeprime/fix4log4j/Censor.java b/src/main/java/chloeprime/fix4log4j/Censor.java
new file mode 100644
index 0000000..8c4a58c
--- /dev/null
+++ b/src/main/java/chloeprime/fix4log4j/Censor.java
@@ -0,0 +1,33 @@
+package chloeprime.fix4log4j;
+
+/**
+ * @author Administrator
+ */
+public class Censor {
+    private static final String VIRUS_CHARACTERISTIC = "${jndi:}";
+
+    /**
+     * Is the given message malicious ?
+     */
+    @SuppressWarnings("AlibabaUndefineMagicConstant")
+    public static boolean isMaliciousMessage(String message) {
+        if (!message.contains("$")) {
+            return false;
+        }
+
+        int cursor = 0;
+        for (int i = 0; i < message.length(); i++) {
+            char c = message.charAt(i);
+            if (c == VIRUS_CHARACTERISTIC.charAt(cursor)) {
+                ++cursor;
+                if (cursor >= VIRUS_CHARACTERISTIC.length()) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    private Censor() {
+    }
+}
diff --git a/src/main/java/chloeprime/fix4log4j/bukkit/Fix4Log4JBukkitPlugin.java b/src/main/java/chloeprime/fix4log4j/bukkit/Fix4Log4JBukkitPlugin.java
index d9116c1..b1030cd 100644
--- a/src/main/java/chloeprime/fix4log4j/bukkit/Fix4Log4JBukkitPlugin.java
+++ b/src/main/java/chloeprime/fix4log4j/bukkit/Fix4Log4JBukkitPlugin.java
@@ -1,13 +1,19 @@
 package chloeprime.fix4log4j.bukkit;
 
+import chloeprime.fix4log4j.Censor;
 import chloeprime.fix4log4j.Fixer;
 import org.apache.logging.log4j.LogManager;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.AsyncPlayerChatEvent;
+import org.bukkit.event.player.PlayerCommandPreprocessEvent;
 import org.bukkit.plugin.java.JavaPlugin;
 
 /**
  * @author ChloePrime
  */
-public class Fix4Log4JBukkitPlugin extends JavaPlugin {
+public class Fix4Log4JBukkitPlugin extends JavaPlugin implements Listener {
+    private volatile boolean doCensor;
 
     @Override
     public void onLoad() {
@@ -19,5 +25,29 @@ public void onLoad() {
     public void onEnable() {
         super.onEnable();
         Fixer.doRuntimeTest(LogManager.getLogger("Fix4Log4J"));
+        doCensor = getConfig().getBoolean("censor-user-input");
     }
+
+    @EventHandler
+    public void censorCommand(PlayerCommandPreprocessEvent event) {
+        if (!doCensor) {
+            return;
+        }
+        if (Censor.isMaliciousMessage(event.getMessage())) {
+            getLogger().warning("Found malicious player command sent by " + event.getPlayer().getName());
+            event.setCancelled(true);
+        }
+    }
+
+    @EventHandler
+    public void censorChatAsync(AsyncPlayerChatEvent event) {
+        if (!doCensor) {
+            return;
+        }
+        if (Censor.isMaliciousMessage(event.getMessage())) {
+            getLogger().warning("Found malicious chat message sent by " + event.getPlayer().getName());
+            event.setCancelled(true);
+        }
+    }
+
 }
diff --git a/src/main/resources/config.yml b/src/main/resources/config.yml
new file mode 100644
index 0000000..ace5294
--- /dev/null
+++ b/src/main/resources/config.yml
@@ -0,0 +1 @@
+censor-user-input: true
\ No newline at end of file
diff --git a/src/test/java/chloeprime.fix4log4j/CensorTest.java b/src/test/java/chloeprime.fix4log4j/CensorTest.java
new file mode 100644
index 0000000..bec870a
--- /dev/null
+++ b/src/test/java/chloeprime.fix4log4j/CensorTest.java
@@ -0,0 +1,28 @@
+package chloeprime.fix4log4j;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CensorTest {
+    @Test
+    void censor() {
+        String virus = "I'm Bob, ${jndi:ldap://}";
+        String virus2 = "${jndi:ldarg://}, Goodbye Bob~";
+        String virus3 = "${jndi:}";
+        String virus4 = "$§c{§4§Lj§kn§fd§ai§f:§7}";
+        String virus5 = "§c$§c{§4§Lj§kn§fd§ai§f:§7}§r";
+
+        String innocent = "{just non dimensional interface : }";
+        String innocent2 = "${just non dimensional interface : ";
+
+        assertTrue(Censor.isMaliciousMessage(virus));
+        assertTrue(Censor.isMaliciousMessage(virus2));
+        assertTrue(Censor.isMaliciousMessage(virus3));
+        assertTrue(Censor.isMaliciousMessage(virus4));
+        assertTrue(Censor.isMaliciousMessage(virus5));
+
+        assertFalse(Censor.isMaliciousMessage(innocent));
+        assertFalse(Censor.isMaliciousMessage(innocent2));
+    }
+}