On Tuesday 3 October 2023 at 19:38 UTC, a WebSocket connection flood targeted a sports betting customer in Iberia. The attack peaked at 558.4 million requests per second and lasted 53 minutes. Traffic originated from 3201 autonomous systems in 78 countries, predominantly compromised cloud VMs.
| Vector | WebSocket connection flood |
| Peak | 558.4 million requests per second |
| Duration | 53 min |
| Time to mitigation | 0.560 s |
| Attack traffic reaching origin | 0.044% |
| Legitimate traffic challenged | 0.46% |
Timeline
The attack was preceded by a ransom note demanding payment in Monero. Request rates on the targeted routes exceeded their hourly baseline by a factor of 329 within 15 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
- Add a dedicated rate limit for the targeted route.
- Keep origin IPs out of public DNS history.
- Enable authenticated origin pulls.
Interesting that most attacks are under ten minutes. Our experience is similar.