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.
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.
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.
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.
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