On Sunday 5 September 2021 at 08:49 UTC, a HTTP POST flood targeted a healthcare portal customer in Southeast Asia. The attack peaked at 644.0 million requests per second and lasted 18 minutes. Traffic originated from 2202 autonomous systems in 33 countries, predominantly hijacked home routers.
| Vector | HTTP POST flood |
| Peak | 644.0 million requests per second |
| Duration | 18 min |
| Time to mitigation | 0.066 s |
| Attack traffic reaching origin | 0.079% |
| Legitimate traffic challenged | 0.53% |
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 411 within 24 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.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable log streaming to your SIEM for faster correlation.
Thanks — sharing this with our on-call team.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Great to hear, thanks for sharing your experience.
Do you publish the edge IP ranges in a machine-readable format?
Carpet bombing is nasty. Good to see a clear explanation of it.
Good question. We will cover that in a follow-up post.