On Thursday 28 December 2023 at 19:15 UTC, a HTTP POST flood targeted a crypto exchange customer in the Nordics. The attack peaked at 587.1 million requests per second and lasted 107 minutes. Traffic originated from 3884 autonomous systems in 56 countries, predominantly a headless-browser farm.
| Vector | HTTP POST flood |
| Peak | 587.1 million requests per second |
| Duration | 107 min |
| Time to mitigation | 0.322 s |
| Attack traffic reaching origin | 0.073% |
| Legitimate traffic challenged | 0.54% |
Timeline
The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 120 within 13 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
- Enable log streaming to your SIEM for faster correlation.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.
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.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
The point about origin IPs leaking through certificate transparency logs is underrated.