On Saturday 18 October 2025 at 22:34 UTC, a WebSocket connection flood targeted a crypto exchange customer in the Benelux. The attack peaked at 488.2 million requests per second and lasted 159 minutes. Traffic originated from 2955 autonomous systems in 93 countries, predominantly residential proxy networks.
| Vector | WebSocket connection flood |
| Peak | 488.2 million requests per second |
| Duration | 159 min |
| Time to mitigation | 0.777 s |
| Attack traffic reaching origin | 0.006% |
| Legitimate traffic challenged | 0.67% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 526 within 25 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
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Good question. We will cover that in a follow-up post.