A Smurf attack is a type of distributed denial-of-service (DDoS) Applications Layer attack that capitalizes on ICMP (Internet Control Message Protocol) to flood a target system with traffic. The attackers first obtain the source IP address of the victim, and then send the victim's IP address to a network broadcast IP address so it becomes flooded with a tsunami of packets.The packet is made of an ICMP ping message, which commands the network nodes to send a reply. This process effectively creates an infinite loop that overwhelms a network with constant requests as all the hosts on the network reply.
Named after the malware DDos_Smurf, the Smurfs cartoon series shows how a group of cute tiny blue creatures use their strength in numbers to defend themselves against much larger enemies. This attack uses simple amplification of the network broadcast IP to overwhelm the victim’s network during the attack. The attack is far from cute, and can result in almost total downtime during the entire length of the attack. The attackers can scale the amplification by ensuring the network broadcast has sufficient capacity to overwhelm the victims network.
Although no actual damage to data typically occurs during a Smurf attack, the network will be done, and the attackers can use the chaos to launch other more dangerous attacks with a payload at the same time.
Anatomy of a Smurf Attack
1. Initial Stage: Reconnaissance
Before launching a Smurf Attack, assailants conduct bot based reconnaissance activities to identify potential targets and vulnerabilities within a network. The victim needs to have a static IP, or at the very least a smaller range of operational IP for the attack to be effective. This early reconnaissance activity is very easy to spot, and effectively hides as regular Ping commands.
2. Execution: The Smurfing Technique
Armed with the reconnaissance data, attackers leverage intermediary networks to conceal their identity. The actual attack involves broadcasting ICMP requests to multiple hosts simultaneously, creating the desired level of amplification to bring down the victim’s network.
3. Amplification Effect
The broadcast nature of the ICMP requests causes a simple amplification, as each request triggers multiple responses. This multiplication effect results in a deluge of traffic directed towards the victim.
Smurf Attack Indicator
Spotting a Smurf attack requires a keen eye. Look out for the following:
- Reconnaissance activity that systematically pings every IP over and over again
- sudden spikes in network traffic,
- sluggish internet speed,
- unresponsive servers.
Mitigating Smurf Attacks: Proactive Strategies
1. Network Segmentation
Implementing network segmentation helps contain the impact of a Smurf Attack by isolating critical components. This strategic segmentation acts as a deterrent, limiting the lateral movement of the attack.
2. Ingress Filtering
Enforcing strict ingress filtering at network entry points can significantly mitigate Smurf Attacks. By blocking spoofed IP addresses at the network perimeter, organizations can thwart potential attackers.
3. Traffic Monitoring and Anomaly Detection
Continuous monitoring of network traffic and deploying anomaly detection mechanisms enable swift identification of unusual patterns indicative of a Smurf Attack. Early detection facilitates prompt response and mitigation.