How Cloudflare Killed a 7.3Tbps Monster
Cloudflare DDoS
23 czerwca 2025Author: Łukasz Grochal

Cloudflare mitigated the largest recorded DDoS attack in history—a 7.3 Tbps assault targeting a financial institution, surpassing the previous 3.47 Tbps record. Key details:


  • Attack Composition: Primarily UDP reflection/amplification (DNS, NTP, CLDAP) + TCP SYN floods


  • Geographic Spread: 190+ countries, with 40% of traffic originating from cloud providers


  • Defense Strategy:


    • Edge-based ML filtering dropped malicious packets in <3ms
    • Anycast rerouting distributed load across 300+ PoPs
    • Stateful TCP Challenge mitigated SYN floods without CAPTCHAs


The attack lasted 37 minutes, but zero customer downtime occurred. Cloudflare warns multi-vector mega-attacks are becoming the norm