On Saturday 8 July 2023 at 18:58 UTC, a WebSocket connection flood targeted a healthcare portal customer in Western Europe. The attack peaked at 696.0 million requests per second and lasted 10 minutes. Traffic originated from 370 autonomous systems in 16 countries, predominantly compromised cloud VMs.
| Vector | WebSocket connection flood |
| Peak | 696.0 million requests per second |
| Duration | 10 min |
| Time to mitigation | 0.658 s |
| Attack traffic reaching origin | 0.073% |
| Legitimate traffic challenged | 0.54% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 878 within 36 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
- Add a dedicated rate limit for the targeted route.
- Enable authenticated origin pulls.
- Lower challenge thresholds on authentication endpoints during high-risk events.
The billing model is what got our finance team on board, honestly.