On Sunday 13 November 2022 at 02:40 UTC, a HTTP/2 rapid reset targeted a ticketing customer in the UK. The attack peaked at 76.8 million requests per second and lasted 65 minutes. Traffic originated from 2469 autonomous systems in 29 countries, predominantly mobile carrier ranges.
| Vector | HTTP/2 rapid reset |
| Peak | 76.8 million requests per second |
| Duration | 65 min |
| Time to mitigation | 0.393 s |
| Attack traffic reaching origin | 0.051% |
| Legitimate traffic challenged | 0.59% |
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 543 within 30 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
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Is the risk score exposed in the logs so we can build our own dashboards on it?
The point about origin IPs leaking through certificate transparency logs is underrated.
Verified good bots and allow-listed partners bypass challenges entirely.