Smurf DDoS Attack?

A Smurf attack is a type of Distributed Denial of Service, or DDoS, attack. It seeks to knock your entire network offline with the intention of rendering it inoperable. When compared against other types of DDoS attacks, a Smurf attack differs in that it leverages vulnerabilities. The specific vulnerabilities in question exist within the internet protocol (IP) and Internet Control Message Protocol (ICMP). Additionally, a Smurf attack is called such due to the malware that first allowed these attacks to occur. In a ping flood, no malware is needed to pull off the attack.

How Does a Smurf Attack Work?

In some ways, a Smurf attack is similar to another Denial-of-Service tactic, the ping flood. Just like the ping flood, the target is flooded with ICMP echo requests. Where it differs from a ping flood, however, is that the damage is greater with a Smurf attack due to vulnerability exploits. There is also a variation of a Smurf attack, called a Fraggle attack, that uses UDP instead of ICMP. This isn’t as common, though, and for the purpose of this article we will focus on the regular Smurf attack.

The Smurf attack follows a rather rudimentary set of steps.

  • The Smurf malware forms a malicious ICMP packet. The packet is attached to a false IP address, a tactic the Information Security (InfoSec) community calls “spoofing.” The spoofed packet is actually targeting the static IP address of the victim’s machine/network.
  • The threat actor begins sending the spoofed, malware-laden ICMP packets to the IP broadcast network.
  • The spoofed ICMP contains a ping request, i.e. a request that requires a response from the network nodes, then sends the request to all network hosts.
  • The target IP address receives the requests, and because of the maliciously crafted ICMP packets, continues to receive the requests.
  • Eventually, the requests overload the target device and render it inoperable as no traffic can get through besides the Smurf attack traffic.

What helps the Smurf attack is the number of hosts on the network. It is simple logic really: the more hosts, the more responses that flood the target IP address. This will determine just how quickly the network is knocked offline.

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How Can a Smurf Attack Be Mitigated?

There are multiple strategies that can be employed to reduce the likelihood of a Smurf attack. The first is disabling IP broadcasting at all network nodes. Legacy devices may have IP broadcasting enabled by default, so it is necessary to go to each one and disable it. You should also configure your network devices to not respond to ICMP echo requests.

This on its own is not enough, however, as cybercriminals are incredibly savvy individuals. You could shell out for expensive detection services, but it still doesn’t solve the key issue. The issue here is that your static IP is known by threat actors and can thus be targeted.

FAQs(Frequently Asked Questions)

Yes, the reason why it is considered a DDoS attack has to do with how many machines are involved. In a simple DoS attack, there is only one machine that is attempting to disrupt a system or network. In a DDoS attack, however, multiple machines (called zombies) form a botnet and attack the target. Because a Smurf attack forced all network devices to take part in attacking the host IP address, it is classified as a DDoS attack.
In the 1990s, the original author of the Smurf malware named it so. The individual in question, who went by the hacker ID TFreak, thought the attack was essentially smaller attackers overloading a large target. It made him think of the cartoon Smurfs that are known the world over for their tiny size, as well as their effectiveness when banding together.