On Tuesday 11 February 2025 at 13:32 UTC, a HTTP/2 rapid reset targeted a developer platform customer in North America. The attack peaked at 861.7 million requests per second and lasted 108 minutes. Traffic originated from 2482 autonomous systems in 37 countries, predominantly mobile carrier ranges.
| Vector | HTTP/2 rapid reset |
| Peak | 861.7 million requests per second |
| Duration | 108 min |
| Time to mitigation | 0.587 s |
| Attack traffic reaching origin | 0.018% |
| Legitimate traffic challenged | 0.12% |
Timeline
The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 394 within 6 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
- Keep origin IPs out of public DNS history.
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
The point about origin IPs leaking through certificate transparency logs is underrated.
Solid runbook advice. The DNS-at-2am point hit home.
Thanks! Yes — the risk score and its components are included in every log record.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Could you share the dataset behind the percentages?
Good question. We will cover that in a follow-up post.
Solid runbook advice. The DNS-at-2am point hit home.
Any plans to support per-tenant limits keyed on a JWT claim?
Would love a follow-up on how you handle HTTP/3 fingerprinting.
Our auditors asked for exactly this kind of incident evidence under DORA.