On Monday 20 June 2022 at 22:13 UTC, a HTTP/2 rapid reset targeted a online casino customer in the Nordics. The attack peaked at 155.3 million requests per second and lasted 125 minutes. Traffic originated from 890 autonomous systems in 31 countries, predominantly a headless-browser farm.
| Vector | HTTP/2 rapid reset |
| Peak | 155.3 million requests per second |
| Duration | 125 min |
| Time to mitigation | 0.913 s |
| Attack traffic reaching origin | 0.065% |
| Legitimate traffic challenged | 0.09% |
Timeline
The attack was preceded by a breaking political story. Request rates on the targeted routes exceeded their hourly baseline by a factor of 398 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 121 ms during the first minute, then normal service.
Recommendations
- Keep origin IPs out of public DNS history.
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.