On Wednesday 28 May 2025 at 05:07 UTC, a HTTP POST flood targeted a developer platform customer in the UK. The attack peaked at 390.1 million requests per second and lasted 132 minutes. Traffic originated from 804 autonomous systems in 112 countries, predominantly a rented booter service.
| Vector | HTTP POST flood |
| Peak | 390.1 million requests per second |
| Duration | 132 min |
| Time to mitigation | 0.512 s |
| Attack traffic reaching origin | 0.025% |
| Legitimate traffic challenged | 0.50% |
Timeline
The attack was preceded by a breaking political story. Request rates on the targeted routes exceeded their hourly baseline by a factor of 517 within 21 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
- Review allow-listed partner ranges quarterly.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable log streaming to your SIEM for faster correlation.
Would love a follow-up on how you handle HTTP/3 fingerprinting.
Thanks! Yes — the risk score and its components are included in every log record.
The point about origin IPs leaking through certificate transparency logs is underrated.
The billing model is what got our finance team on board, honestly.
Great write-up. We saw almost the same pattern on our login endpoint last month.