Cloudflare announced Wednesday that it detected and mitigated the largest distributed denial of service (DDoS) attack in history, reaching 29.7 terabits per second (Tbps).
The web infrastructure and security company said the activity originated from a rental DDoS botnet known as AISURU, which has been linked to numerous high-volume DDoS attacks over the past year. The attack lasted 69 seconds. The target of the attack was not disclosed.
This botnet primarily targets telecom providers, gaming companies, hosting providers, and financial services. Cloudflare also tackled a 14.1 Bpps DDoS attack from the same botnet. AISURU is believed to utilize a large network of an estimated 1 million to 4 million infected hosts worldwide.
“The 29.7 Tbps was a UDP carpet bombing attack bombing an average of 15,000 destination ports per second,” Omer Joachimik and Jorge Pacheco said. “The distributed attack randomized various packet attributes to evade defenses.”
Cloudflare has mitigated a total of 2,867 Aisuru attacks since the beginning of the year, of which 1,304 mass attacks were initiated from botnets in the third quarter of 2025 alone. A total of 8.3 million DDoS attacks were blocked during the period, a 15% increase from the previous quarter and a 40% increase from last year.
In 2025, 36.2 million DDoS attacks were stopped, including 1,304 network-layer attacks greater than 1 Tbps, up from 717 in Q1 2025 and 846 in Q2 2025. Here are some of the other notable trends observed in Q3 2025:
The number of DDoS attacks over 100 million packets per second (Mpps) increased 189% quarter over quarter. Most attacks (71% of HTTP DDoS and 89% of network layer attacks) end within 10 minutes. Seven of the top 10 DDoS sources are located within Asia, including Indonesia, Thailand, Bangladesh, Vietnam, India, Hong Kong, and Singapore. The other three sources are Ecuador, Russia, and Ukraine. DDoS attacks against the mining, minerals, and metals industry have skyrocketed, making it the 49th most attacked sector in the world. The automotive industry has seen the highest increase in DDoS attacks, making it the sixth most attacked industry in the world. DDoS attack traffic against artificial intelligence (AI) companies surged 347% in September 2025 Information technology, telecommunications, gambling, gaming, and internet services topped the list of most attacked sectors. China, Türkiye, Germany, Brazil, the United States, Russia, Vietnam, Canada, South Korea and the Philippines were the most attacked countries. Almost 70% of HTTP DDoS attacks originate from known botnets.
“We have entered an era in which DDoS attacks are rapidly increasing in sophistication and scale beyond what was imaginable just a few years ago,” Cloudflare said. “Many organizations face challenges in responding to this evolving threat landscape.”
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