Smurf attack: What is it, and how does it work?

Smurf attack explained 

The Smurf attack is a popular protocol-based type of DDoS (Distributed Denial of Service) attack. Through it, attackers aim to bring down their targets and make the network resources unavailable for regular users. Additionally, it is a huge threat to the finances and reputation of the attacked online organization.

The Smurf attack works by taking advantage of the Internet Control Message Protocol (ICMP). The attacker sends large amounts of ping data packets with the forged IP address of the victim to one or multiple devices. All of them return an answer to the server, and the traffic is increasing massively. As a result, the resources of the server are overloaded, and the normal function is disturbed. Finally, the victim goes down, and it is incapable of answering the users’ requests.

How does it work? 

The Smurf DDoS attack is initiated with software – Smurf malware. It is implemented for directing large amounts of traffic to the target server. It replaces the IP address of the packets of data with the forged IP address of the victim.

Data packets are transferred to a broadcast IP address of a router and then spread to each device that is connected to the specific network. So, as a result, the attack gains a lot more strength. 

All of the computers, mobiles, IoT, and other devices that received the data packets respond to the server of the victim due to the fact the forged IP address is included in the data. 

The devices send an enormous amount of queries to the victim. That is the exact goal of the attacker. Unfortunately, the numerous queries are causing serious difficulty for the victim, and it becomes really challenging to process them. Starting with bandwidth, the resources are finished, and the server is down. 

Due to the way it works, the Smurf attack is described as a resource consumer attack. The reason for that is the ICMP echo requests produce huge ping traffic that does not leave enough bandwidth for serving the regular users.

How to prevent a Smurf attack?

There are several things you could do to mitigate the Smurf attack. They are the following:

• Be aware and keep an eye on some indicators such as server or router crashing and bandwidth problems. That could be a sign of an occurring Smurf attack.
• A Monitoring service could help you completely examine your traffic for irregular volume, signature on data packets, or uncommon behavior.
• Make sure to get suitable bandwidth that could manage traffic spikes.
• Choosing an efficient load balancing system is going to help for distributing the massive traffic and provide redundancy.
• You can implement a DDoS-protected DNS service for keeping your DNS servers safe from DDoS attacks.
• You could deactivate IP addresses broadcast on networks’ routers and firewalls.
• Adjust your firewall perimeter and disallow pings coming from outside the network.
• Forbid IP broadcast requests (ICMP) for your operating system (OS).
• Forbid your hosts and routers from answering ICMP echo requests.