On Wednesday 21 February 2024 at 01:04 UTC, a WebSocket connection flood targeted a sports betting customer in the Nordics. The attack peaked at 975.8 million requests per second and lasted 75 minutes. Traffic originated from 1166 autonomous systems in 103 countries, predominantly misconfigured open reflectors.
| Vector | WebSocket connection flood |
| Peak | 975.8 million requests per second |
| Duration | 75 min |
| Time to mitigation | 0.771 s |
| Attack traffic reaching origin | 0.004% |
| Legitimate traffic challenged | 0.51% |
Timeline
The attack was preceded by a hacktivist channel announcing the target. Request rates on the targeted routes exceeded their hourly baseline by a factor of 742 within 24 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
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Enable log streaming to your SIEM for faster correlation.
- Keep origin IPs out of public DNS history.
- Add a dedicated rate limit for the targeted route.