On Thursday 2 June 2022 at 20:20 UTC, a HTTP/2 rapid reset targeted a online casino customer in the Benelux. The attack peaked at 663.1 million requests per second and lasted 35 minutes. Traffic originated from 1240 autonomous systems in 19 countries, predominantly mobile carrier ranges.
| Vector | HTTP/2 rapid reset |
| Peak | 663.1 million requests per second |
| Duration | 35 min |
| Time to mitigation | 0.413 s |
| Attack traffic reaching origin | 0.089% |
| Legitimate traffic challenged | 0.10% |
Timeline
The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 824 within 22 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
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Keep origin IPs out of public DNS history.
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.
Interesting that most attacks are under ten minutes. Our experience is similar.
Thanks — sharing this with our on-call team.