On Wednesday 3 November 2021 at 19:27 UTC, a HTTP/2 rapid reset targeted a healthcare portal customer in Latin America. The attack peaked at 590.3 million requests per second and lasted 150 minutes. Traffic originated from 2985 autonomous systems in 21 countries, predominantly misconfigured open reflectors.
| Vector | HTTP/2 rapid reset |
| Peak | 590.3 million requests per second |
| Duration | 150 min |
| Time to mitigation | 0.405 s |
| Attack traffic reaching origin | 0.040% |
| Legitimate traffic challenged | 0.06% |
Timeline
The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 106 within 8 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
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.
- Review allow-listed partner ranges quarterly.
Could you share the dataset behind the percentages?
Could you share the dataset behind the percentages?
Thanks — sharing this with our on-call team.
Great to hear, thanks for sharing your experience.