On Friday 4 March 2022 at 21:20 UTC, a WebSocket connection flood targeted a sports betting customer in the UK. The attack peaked at 330.3 million requests per second and lasted 114 minutes. Traffic originated from 2278 autonomous systems in 24 countries, predominantly misconfigured open reflectors.
| Vector | WebSocket connection flood |
| Peak | 330.3 million requests per second |
| Duration | 114 min |
| Time to mitigation | 0.210 s |
| Attack traffic reaching origin | 0.053% |
| Legitimate traffic challenged | 0.69% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 328 within 6 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.
- Review allow-listed partner ranges quarterly.
- Lower challenge thresholds on authentication endpoints during high-risk events.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Our auditors asked for exactly this kind of incident evidence under DORA.
Good question. We will cover that in a follow-up post.