On Monday 31 May 2021 at 11:35 UTC, a HTTP POST flood targeted a sports betting customer in North America. The attack peaked at 615.4 million requests per second and lasted 53 minutes. Traffic originated from 2777 autonomous systems in 114 countries, predominantly residential proxy networks.
| Vector | HTTP POST flood |
| Peak | 615.4 million requests per second |
| Duration | 53 min |
| Time to mitigation | 0.244 s |
| Attack traffic reaching origin | 0.056% |
| Legitimate traffic challenged | 0.02% |
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 662 within 9 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.
- Review allow-listed partner ranges quarterly.
- Keep origin IPs out of public DNS history.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Good question. We will cover that in a follow-up post.