Cloudflare thwarts largest DDoS attack ever recorded

DDoS attack
(Image credit: FrameStockFootages / Shutterstock)

The web infrastructure company Cloudflare has revealed its autonomous edge DDoS protection systems were able to automatically detect and mitigate the largest DDoS attack it has encountered so far.

Back in July, the company was able to thwart a 17.2 million request-per-second (rps) DDoS attack which was almost three times larger than any previously recorded DDoS attacks

To put this in perspective, Cloudflare points out in a new blog post that it served 25m HTTP requests per second on average during Q2 2021 which means the attack generated 68 percent of its Q2 average rps rate of legitimate HTTP traffic.

The botnet used to launch this attack has reappeared at least twice in recent weeks and Cloudflare says that it was also used to target one of its customers in the web hosting industry with an HTTP DDoS attack that peaked just below 8m rps.

Automated DDoS detection and mitigation

Cloudflare was able to stop this massive attack and others like it thanks to its autonomous edge DDoS protection systems that are capable of automatically detecting and mitigating DDoS attacks.

The system is powered by the company's own denial of service daemon (dosd) which is a home-grown software-defined daemon. Cloudflare runs a unique dosd instance in every server housed in its data centers around the world. 

Each dosd instance can independently analyze traffic samples that are out-of-path and by doing so, this allows the company to asynchronously scan for DDoS attacks without introducing latency or impacting performance. Findings related to DDoS attacks are then shared between the dosd instances in a data center to serve as a form of proactive threat intelligence sharing.

Due to the global scale and reliability of its network along with this autonomous approach, Cloudflare can mitigate attacks that reach 68 percent of its average per-second-rate and higher without the need for manual mitigation by its staff.

While Cloudflare was able to stop this 17.2m rps DDoS attack, there will likely be larger attacks in the future as cybercriminals devise new attack methods and the botnets used to carry out these attacks continue to add more IoT and other devices to their ranks. 

Anthony Spadafora

After working with the TechRadar Pro team for the last several years, Anthony is now the security and networking editor at Tom’s Guide where he covers everything from data breaches and ransomware gangs to the best way to cover your whole home or business with Wi-Fi. When not writing, you can find him tinkering with PCs and game consoles, managing cables and upgrading his smart home. 

Read more
DDoS Attack
World's largest DDoS attack blocked, Cloudflare claims
An image of network security icons for a network encircling a digital blue earth.
Standing strong against hyper-volumetric DDoS attacks
An image of security icons for a network encircling a digital blue earth.
Best DDoS protection of 2025
Web DDoS attacks see major surge as AI allows more powerful attacks
DDoS attack
Europol announces takedown of major DDoS-for-hire network
Insecure network with several red platforms connected through glowing data lines and a black hat hacker symbol
Cisco, ASUS, QNAP, and Synology devices hijacked to major botnet
Latest in Pro
An American flag flying outside the US Capitol building against a blue sky
Sean Plankey selected as CISA director by President Trump
A young man working on laptop in office writing notes
Ending the fix/break cycle of End User Computing support
OpenAI
OpenAI wants to help your business build its next generation of AI agents
Ai tech, businessman show virtual graphic Global Internet connect Chatgpt Chat with AI, Artificial Intelligence.
Nation-state threats are targeting UK AI research
A hand reaching out to touch a futuristic rendering of an AI processor.
Business investors are positive about AI’s impact on the economy
Scam alert
Fake jobs and phone calls: How Americans lost $12.5 bn to fraud in 2024
Latest in News
Mufasa is joined by another lion, a monkey and a bird in this promotional image
Mufasa: The Lion King prowls onto Disney+ as it finally gets a streaming release date
An American flag flying outside the US Capitol building against a blue sky
Sean Plankey selected as CISA director by President Trump
An Nvidia GeForce RTX 4060 on a table with its retail packaging
Nvidia RTX 5060 GPU spotted in Acer gaming PC, suggesting rumors of imminent launch are correct – and that it’ll run with only 8GB of video RAM
Indiana Jones talking to a friend in a university setting with a jaunty smile on his face
New leak claims Indiana Jones and the Great Circle PS5 release will come in April
A close up of the limited edition vinyl turntable wrist watch from AndoAndoAndo
This limited-edition timepiece turns the iconic Technics SL-1200 turntable into a watch, and I want one
A close up of Gemma sitting down in Severance season 2 episode 7
'I'm like Gemma – I'm in the dark': Severance star Dichen Lachman shares disappointing filming update for the popular Apple TV+ show's third season