Cloudflare faced an extraordinary cyberattack so massive that it set a new global record. The DDoS (distributed denial of service) attack reached a peak of 7.3 terabits per second (Tbps)—a terabit being 1,000 gigabits, or 1 trillion bits of data transmitted per second, far surpassing previous attacks and highlighting just how powerful cyber threats have become.
A Record-Breaking Digital Flood
This attack came shortly after Cloudflare published its latest DDoS threat report, which detailed attacks reaching over 6 Tbps and involving billions of packets every second. The target client in Cloudflare’s network was a hosting provider protected by the Magic Transit service. Cloudflare has observed millions of smaller similar attacks, with providers and critical internet infrastructure increasingly being targeted by malicious actors aiming to disrupt services.
While 37.4 terabytes of data might seem manageable in some contexts, delivering that amount in under a minute is staggering. To visualiz, it’s like streaming over 7,400 hours of HD video nonstop, downloading nearly 9.4 million songs in less than a minute, or taking 12.5 million high-resolution photos all within 45 seconds. This kind of traffic surge can overwhelm networks and infrastructure, making effective defenses essential.
Attack Flow
The attack targeted a single IP address and flooded it across thousands of ports—over 21,900 on average per second, peaking at more than 34,500. The assault primarily used UDP floods, a common method to saturate networks. A small fraction of the attack involved reflection and amplification techniques, exploiting known protocols like QOTD, Echo, NTP, and others to magnify the attack’s impact.
UDP flooding is when hackers overwhelm the target with massive volumes of UDP packets, often disrupting normal operations. Reflection & amplification tactics involve exploiting protocols that respond with large amounts of data when queried, such as:
- QOTD (Quote of the Day), an outdated protocol that responds with a short message.
- Echo service which replies with whatever data it receives.
- NTP (Network Time Protocol) uses commands like “monlist” to generate large response sizes.
- IoT Botnets (like Mirai) utilizing compromised devices to flood targets with UDP traffic.
- Portmapper and RIPv1, older network services that can be exploited to amplify attack traffic.
The malicious traffic originated from a vast network of over 122,000 unique IP addresses across more than 5,400 networks worldwide. Nearly half of the traffic came from Brazil and Vietnam, with significant contributions from other countries like Taiwan, China, and the U.S. This global distribution underscores the widespread nature of modern cyber threats.
Response
Cloudflare’ss network architecture played a crucial role in the attack’s swift mitigation. They use a global anycast meaning traffic is directed to the nearest data centers—spreading the load across hundreds of locations worldwide. Systems detect threats automatically, analyzing traffic in real time and utilizing advanced tools that examine incoming packets at the kernel level, quickly identifying patterns indicative of malicious activity.
Once an attack pattern is recognized, systems generate precise “fingerprints” to distinguish malicious traffic from legitimate data, enabling precise blocking of harmful packets efficiently and automatically. This autonomous detection and response system worked seamlessly, stopping the attack in nearly 500 data centers without human intervention, and without causing disruptions to regular users.
This event highlights the importance of having advanced, automated defenses in place. Cloudflare’s goal is to make the internet safer and more resilient for everyone with technology protects not just individual websites but entire networks—keeping services online, fast, and secure against even the most massive threats.
To learn more about Cloudflare’s analysis and response, as well as tools for online and cloud protection, visit their website here.
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