Table of Contents
Introduction
The words “fraggle” or “smurf” might trigger fond memories of two popular childhood TV shows from the 80’s: Fraggle Rock and The Smurfs. Afterall, who doesn’t love a muppet or a feisty, little blue cartoon character? However, there’s nothing to love about Fraggle or Smurf DDoS attacks.
Beyond the cute names, both types of DDoS attacks have many other things in common. Understanding the similarities and differences are critical to ensure your organization is protected against these attacks.
We already explored Smurf attacks in depth in a prior blog. Here, we’ll dig into how Fraggle attacks unfold, how they compare to Smurf attacks, and the impact this type of DDoS attack can have on organizations. We’ll also offer guidance on how to detect and protect against this cyber threat.
Understanding Fraggle Attacks
A Fraggle attack is a type of denial-of-service attack that takes advantage of the User Datagram Protocol (UDP) to flood a victim’s network with illegitimate traffic. As with all DDoS attacks, the goal of this attack type is to deny service to legitimate users by slowing down or crashing the server.
How it Exploits UDP
A Fraggle attack exploits the User Datagram Protocol (UDP) at Layer 4 of the OSI model. Unlike Transmission Control Protocol (TCP) which requires a three-way handshake between the source and destination before data can be transmitted and an end-to-end connection, UDP doesn’t need an open session and end-to-end connection. This makes UDP ideal for time-sensitive applications like VoIP, online gaming, and media streaming as well as for DNS lookups. It’s also great for broadcasts because it doesn’t formally establish a connection before the data is transferred.
Under normal circumstances:
- UDP sends packets directly to a network’s broadcast address
- UDP does not establish a connection first
- UDP does not indicate the order of the packets or check to see if they arrived
In a nutshell, using UDP, a computer can simply start sending data to another computer in independent units, also referred to as “datagrams.”
However, this convenience and speed comes at a price. UDP’s lack of connection requirements and data verification make it easy to exploit. Attackers can send a massive amount of UDP packets to a targeted server without first getting the server’s permission to begin communication.
Fraggle vs Smurf Attacks
If you read our blog on Smurf attacks, you might be thinking Fraggle attacks sound very similar. You’re right, they are. In addition to being named after cute characters, both types of DDoS attacks exploit IP vulnerabilities to target a victim’s server with a flood of spoofed packets for broadcast. The objective is also the same: overwhelm victims with bogus traffic and disrupt service so that legitimate traffic can’t get through.
The main difference between the two types of attacks is the type of traffic used to overload the network. Fraggle attacks use UDP traffic, specifically targeting ports like 7 (Echo) and 19 (Chargen). Smurf attacks use Internet Control Message Protocol (ICMP) traffic.
How a Fraggle DDoS Attack Works
In a Fraggle DDoS attack, the attacker sends a spoofed UDP packet to the broadcast address of a network, requesting responses from multiple devices. When the devices respond back to the victim, the network becomes flooded with traffic.
The Attack Process
There are four main stages in a Fraggle attack:
- The attacker identifies a target and determines their IP address.
- The attacker fakes, or spoofs, the victim’s IP address and sends a large number of UDP packets from that spoofed IP address to a broadcast address that relays the message to every device on the network.
- As each recipient sends an response back to the broadcast address, the replies are rerouted to the victim.
- The victim’s device becomes overloaded with traffic, which consumes bandwidth and system resources and can take the network down.
The Impact of Fraggle Attacks
Fortunately, modern routers and servers rarely forward packets directed at their broadcast addresses, so most networks are now immune to Fraggle attacks. That said, if an older device is still connected to the network without your knowledge, or if devices aren’t up to date, a Fraggle DDoS attack can negatively impact networks, servers, and organizations.
As we’ve already discussed, the immediate impact of a Fraggle attack is denial of service. Depending on the sophistication and persistence of the attacker, a DDoS attack can last for days, weeks or longer.
Compounding the impact, threat actors may be using the attack as a distraction. While the organization is working on fixing the damage and bringing services back up, a threat actor could be moving laterally within the environment, looking for data to steal or encrypt or other systems to exploit and damage.
Ultimately, the impact on an organization could include operational costs to mitigate and deal with the aftermath of an attack, reputational damage, and lost revenue.
Mitigating Fraggle DDoS Attacks
There are several best practices and tools security teams can use to mitigate and prevent Fraggle DDoS attacks, including the following:
Preventative measures
Practical tips like traffic filtering, rate limiting, and updating hardware can go a long way to preventing Fraggle attacks. Specifically:
- Filter UDP traffic on ports 7 and 19 that Fraggle attacks commonly target.
- Limit the number of requests a server can accept from a single IP address during a specific period of time.
- Update older network hardware since most newer versions have built-in protections against attacks that use broadcast services to amplify attacks.
- Disable IP-directed broadcast on routers, but that may be a feature you need within your organization so be sure to check first.
Network monitoring capabilities
Continuous monitoring can help detect and respond to DDoS attacks quickly. With an understanding of your baseline traffic, it can sort the good from the bad accurately, and automatically stop spikes in UDP traffic before it has a chance to cause disruptions. IPS and IDS systems are designed to monitor network traffic for suspicious activity and can help detect and mitigate such attacks in real time. Reputable DDoS protection solutions should include network monitoring capabilities, so you don’t need to switch between multiple tools to monitor traffic.
DDoS protection software
A proven DDoS protection solution will mitigate the gamut of DDoS attacks, including Fraggle DDoS attacks, and ensure you stay ahead of emerging threats. The most effective solutions will allow you to maintain uninterrupted service availability even in the midst of a DDoS attack. When coupled with real-time threat intelligence, these solutions can also protect you against follow-on malicious activity including data leakage, ransomware attacks, and other threats to your operations.
Conclusion
A Fraggle attack is a type of denial-of-service attack that takes advantage of the User Datagram Protocol (UDP) to flood a victim’s network with illegitimate traffic, slowing down performance and eventually crashing the network.
UDP is ideal for time-sensitive applications like VoIP, online gaming, and media streaming as well as for DNS lookups. It’s also great for broadcasts because it doesn’t formally establish a connection before the data is transferred communication. However, UDP’s lack of connection requirements and data verification make it easy to exploit. Attackers can send a massive amount of UDP packets to a targeted server without first getting the server’s permission to begin communication.
Fortunately, modern routers and servers rarely forward packets directed at their broadcast addresses, so most networks are now immune to Fraggle attacks. That said, if an older device is still connected to the network without your knowledge, or if devices aren’t up to date, a Fraggle attack can negatively impact networks, servers, and organizations. Fraggle attacks can also be used as a decoy to launch follow-on attacks that cause additional damage.
There are several best practices and technologies to mitigate and prevent ACK flood attacks, including practical tips like traffic filtering, rate limiting, updating hardware, and network monitoring.
However, the most effective way to protect against a gamut of DDoS attacks, including Fraggle attacks, is by implementing an advanced DDoS protection solution with a proven track record. DDoS protection coupled with intelligence to stay ahead of emerging and evolving threats, provides uninterrupted service availability even in the midst of a DDoS attack. Comprehensive DDoS protection can also defend against follow-on attacks that can harm your business. Visit our threat intelligence research center for more information on DDoS defense in depth.
FAQ
A Fraggle attack is a type of denial-of-service attack that takes advantage of the User Datagram Protocol (UDP) to flood a victim’s network with illegitimate traffic.
Fraggle attacks are very similar to Smurf attacks. The main difference is the type of packets sent. In a Fraggle DDoS attack, the attacker sends a spoofed UDP packet to the broadcast address of a network, requesting responses from multiple devices. When the devices respond back to the victim, the network becomes flooded with traffic. Smurf attacks send ICMP packets.
Signs of a Fraggle attack include unexplained crashes, too much traffic coming in and little going out, IP traffic from multiple hosts all using the same IP prefix, and slow server performance.
Due to the volume of UDP traffic that results from a Fraggle attack, overall performance of the network suffers, legitimate users trying to gain access to services may experience slow response time, and eventually service can be disrupted for days, weeks, or even months. There’s also a risk of a secondary attack once threat actors gain entry to the network and the organization is focused on cleaning up the DDoS attack.
Organizations can use best practices and technologies to protect their organization from Fraggle DDoS attacks, including updating network hardware, implementing rate limiting and traffic filtering, network monitoring, and DDoS protection solutions.
Fortunately, modern routers and servers have built-in protections against attacks that use broadcast services to amplify attacks. So, most networks are now immune to Fraggle attacks.
Yes. Purpose-built DDoS protection coupled with intelligence to stay ahead of emerging threats, provides uninterrupted service availability even in the midst of an IP fragmentation DDoS attack. Advanced DDoS protection can also defend against other malicious activity that can harm an enterprise.
