On Sunday 2 May 2021 at 18:25 UTC, a HTTP GET flood targeted a healthcare portal customer in Latin America. The attack peaked at 411.5 million requests per second and lasted 29 minutes. Traffic originated from 634 autonomous systems in 52 countries, predominantly residential proxy networks.
| Vector | HTTP GET flood |
| Peak | 411.5 million requests per second |
| Duration | 29 min |
| Time to mitigation | 0.844 s |
| Attack traffic reaching origin | 0.011% |
| Legitimate traffic challenged | 0.06% |
Timeline
The attack was preceded by a competitor’s product launch. Request rates on the targeted routes exceeded their hourly baseline by a factor of 844 within 7 seconds. The risk score of participating clients crossed the challenge threshold automatically and proof-of-work difficulty rose with origin load.
What the customer saw
A brief increase in p99 latency of 222 ms during the first minute, then normal service.
Recommendations
- Enable authenticated origin pulls.
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.