Answer: A denial-of-service attack
A smurf attack is a specific form of denial-of-service attack in which a large volume of ICMP packets (with the victim's spoofed IP address is swapped in the sender's IP address) are broadcast over a computer network using one of the IP broadcast addresses available on that network.
As a result, any ICMP request (like a ping request) sent via Smurf to the IP broadcast address of the network would prompt all of the computers within that broadcast address block to respond, effectively banning the unsuspecting IP address (and attached computer equipment) of the targeted user during a mountain of misdirected responses, rendering their connection unusable until the deluge of replies stopped. The Smurfs since the creator of the original code that drove the attack, Dan Moschuk, saw the deluge of packets, like the tiny Smurfs, overwhelming a much bigger one Opponent through sheer numbers ̵
Smurf attacks are extremely easy to execute prior to the late 1990s since most networks were poorly configured and unable to resist abuse in such a fashion. Since then, hosts and routers have been routinely configured to respond to ICMP requests addressed to the IP broadcast level or to forward requests they receive.