On Friday 15 October 2021 at 04:50 UTC, a WebSocket connection flood targeted a tax authority portal customer in Southeast Asia. The attack peaked at 273.8 million requests per second and lasted 129 minutes. Traffic originated from 3594 autonomous systems in 61 countries, predominantly a headless-browser farm.
| Vector | WebSocket connection flood |
| Peak | 273.8 million requests per second |
| Duration | 129 min |
| Time to mitigation | 0.180 s |
| Attack traffic reaching origin | 0.080% |
| Legitimate traffic challenged | 0.55% |
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 581 within 20 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
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Enable authenticated origin pulls.
- Keep origin IPs out of public DNS history.
- Lower challenge thresholds on authentication endpoints during high-risk events.
Do you publish the edge IP ranges in a machine-readable format?
Great write-up. We saw almost the same pattern on our login endpoint last month.
Interesting that most attacks are under ten minutes. Our experience is similar.
Our auditors asked for exactly this kind of incident evidence under DORA.
How do you avoid challenging uptime monitors and partners?
Could you share the dataset behind the percentages?
The point about origin IPs leaking through certificate transparency logs is underrated.
Thanks — sharing this with our on-call team.