What Are Smurf Attacks & How to Prevent Them

What is a smurf attack?

A smurf attack is a type of distributed denial of service (DDoS) attack where an attacker sends an avalanche of ping data packets to its target. It does this by spoofing the source IP address of the ping to be the victim’s, and sending it to a network broadcast IP address.

So instead of one computer replying, all hosts on the network reply to the victim. The large volume of reply packets overwhelms the victim’s network and makes it unavailable to legitimate traffic.

It’s named after the Smurfs, a Belgian cartoon show that started in the 1960s about a group of small blue creatures living in a forest who use their strength in numbers to overwhelm much larger opponents.

A smurf attack occurs on level 7, the highest level of the OSI model. This is the application layer, which accounts for the surface data processing as humans interact with software.

How does a smurf attack work?

A smurf attack manipulates the ICMP—the Internet Control Message Protocol, a communications layer for IP addresses to exchange data. It’s used to send operational information about the state of the network, including ping (a request to test the reachability of the target host, also known as ICMP echo requests.) Attacks can start from devices infected with viruses or malware.

Here’s how a basic smurf attack works:

1. The attacker identifies a target and determines their IP address.
2. The attacker then spoofs the target’s IP address and sends a large number of ICMP ping packets to a broadcast address, a special IP address that reaches all hosts on the same network.
3. When the packets are received by the hosts on the network, they respond with their own reply packets (ICMP echo reply packets), which are sent to the victim’s IP address.
4. As more and more hosts on the network respond to the echo requests, the victim’s network becomes overwhelmed with traffic, slowing it down or completely disabling it.

Alternatively, attackers can perform an advanced smurf attack by spoofing more than one IP address. This could be done if they’re targeting a business, a network, a group of people, or a particular online service.

How do you detect a smurf attack?

Monitoring network traffic is usually the best way to detect smurf attacks. You’ll want to look out for unusual patterns of ICMP traffic and large numbers of ping requests sent to a broadcast address.

Doing this manually usually isn’t ideal, especially if you don’t have a large IT department, but standard network monitoring tools should give you access to the traffic data you need.

Alternatively, you can use DDoS protection software, which automatically scans your traffic to alert you when abnormal activity is detected.

Impact of Smurf Attacks on a Business

Like other forms of DDoS attack, smurf DDoS attacks can be lethal for a wide range of business operations.

Networks and servers can be brought down for days. This can have a devastating impact, as staff won’t be able to communicate or access important files. If your website is down, your e-commerce store won’t be able to take orders, losing crucial revenue and loyal customers by the hour.

And when your network is down, its defenses can be, too—which opens the door for hackers to gain access to confidential data and systems. More harmful attacks can end up causing expensive security nightmares.

How to Mitigate Smurf Attacks

1. Use DDoS Prevention Software

The safest and easiest way to detect and prevent smurf attacks is to use DDOS prevention software. Datadome is one of them, and it blocks harmful attacks in real-time. You can use it for AI-enabled insight into anomalous traffic patterns and security threats. It’s made for stopping DDOS attacks with a smart mix of detection, prevention, and mitigation.

2. Improve Overall Cybersecurity

General cybersecurity best practices will help prevent your organizations’ devices from becoming conduits for DDoS smurf attacks. If employees unwittingly download malware or dodgy files, they’re at risk of enabling criminals to launch these attacks from your network.

3. Adjust Traffic Parameters

Technical fixes on the day of the attack are possible, but not ideal.

One quick remedy is to disallow inbound ICMP traffic while you investigate. This can also be done by your ISP, who might be able to help track the source of the attack, or it can be done at the router level. However, it will impact the functionality of your network.