A Smurf attack is a form of distributed denial-of-service (DDoS) attack that occurs at the network layer. Smurfing attacks are named after the malware DDoS.Smurf, which enables hackers to execute them. More widely, the attacks are named after the cartoon characters The Smurfs because of their ability to take down larger enemies by working together.
DDoS Smurf attacks are similar in style to ping floods, which are a form of denial-of-service (DoS) attack. A hacker overloads computer with Internet Control Message Protocol (ICMP) echo requests, also known as pings. The ICMP determines whether data reaches the intended destination at the right time and monitors how well a network transmits data. A Smurf attack also sends ICMP pings but is potentially more dangerous because it can exploit vulnerabilities in the Internet Protocol (IP) and the ICMP.
A “smurf” attack doesn’t have anything to do with those adorable blue cartoon people. Instead, it’s a particular form of DDoS or Distributed Denial of Service attack. Smurf attacks are devastating and employ a very clever exploit that sets them apart from vanilla DDoS attacks.
To understand what makes a smurf attack special, we first need to look at the more mainstream form of this attack.
The internet consists of servers that contain data we all want to access, client devices such as the one you’re using right now, and network equipment that lets them talk to each other.
Servers don’t have an infinite capacity to serve data to client devices. They have limited bandwidth, processing power, and IO speed. This means that if a server can only serve 100 users at a time, the 101st user is denied service.
Normally that’s not a problem these days. Massive data centres now offer the majority of hosting services. Modern server technology allows the server capacity to be scaled up quickly. Servers are also more powerful than ever, making it very unlikely that you will be denied service.
A DDoS attack rope in a massive number of client devices and makes them all try to access the same service at the same time. This artificial demand is usually of the magnitude of what would be possible on the worst day.
You can, in principle, just get a bunch of computers together and launch a DDOS. However, in practice, you can only have an effective DDoS attack by infecting other people’s computers. These so-called “botnets” all wait for the command to attack, and then you can take down a Goliath using millions of David’s.
An ICMP for smurf attack is a form of DDoS attack that overloads network resources by broadcasting ICMP echo requests to devices across the network. Devices that receive the request respond with echo replies, which creates a botnet situation that generates a high ICMP traffic rate.
As a result, the server is flooded with data requests and ICMP packets, which overwhelm the computer network and make it inoperable. This can be particularly problematic for distributed computing systems, which allow devices to act as computing environments and enable users to access resources remotely.
One of the biggest dangers of smurf attacks is that there is usually a long delay between the malware infection and the actual attack. That’s because the attackers need to build up enough infected computers in their army to pull off an effective attack.
This is why many smurf attack trojans also have rootkits built into them. This lets the malware author open up a way for the system to send and receive commands. As you might imagine, it’s therefore very important that computers have effective malware packages on them that prevent Smurf attack software from running in the first place.
In the end, however, it’s up to the network engineers to build safeguards into the network itself. Modern firewalls and edge network devices can filter out malicious traffic. They can be set to ignore the types of compromised packets that would trigger a packet flood in the first place.
There also needs to be effective monitoring of network traffic to ensure that any weird behaviour is detected and dealt with quickly. It can also help organizations buy scalable bandwidth and server capacity capable of dealing with short-term bursts in traffic caused by malicious attacks until they can be stopped.
Servers should also be spread out into different physical data centres and have redundancy so that if one does go down in a Smurf attack, there’s no denial of service.
It’s possible to accidentally download the Smurf Trojan from an unverified website or via an infected email link. Typically, the program will remain dormant on a computer until activated by a remote user; as a result, many Smurfs come bundled with rootkits, allowing hackers to create backdoors for easy system access. One way to combat a Smurf attack is to turn off IP broadcast addressing on every network router. This function is rarely used, and if turned off it is not possible for the attack to overwhelm a network.
If a Smurf DDoS attack does succeed, it can cripple company servers for hours or days, resulting in lost revenue and customer frustration — what’s more, this kind of attack may also be a cover-up for something more sinister, such as theft of files or other intellectual property (IP). Dealing with Smurf and similar DDoS attacks requires a robust prevention strategy that is able to monitor network traffic and detect any oddities, for example packet volume, behaviour and signature; many malware bots exhibit specific characteristics, and the right security service can help shut down a Smurf or other DDoS attack before it begins.
We almost forgot. Throughout this whole article, you’ve probably wondered why this type of attack has earned the nickname “Smurf” attack. At first, we thought it might be because the flood of internet packets might have been seen as an army of Smurfs, but the real story seems to be that the early exploit software used to perpetrate these attacks was simply called Smurf.
The package was apparently called this because the small packets caused big problems, just like the Smurfs in the cartoon. So maybe my first instinct wasn’t that far off!
Smurf attacks aren’t really something that end-users can do anything about or really need to understand on a precise technical level. We certainly don’t! However, the next time you hear that service stopped working because of a flood, amplification, or “Smurf” attack, you’ll know exactly what that means.