On Thursday 21 July 2022 at 11:25 UTC, a WebSocket connection flood targeted a crypto exchange customer in the UK. The attack peaked at 598.9 million requests per second and lasted 45 minutes. Traffic originated from 3570 autonomous systems in 82 countries, predominantly mobile carrier ranges.
| Vector | WebSocket connection flood |
| Peak | 598.9 million requests per second |
| Duration | 45 min |
| Time to mitigation | 0.276 s |
| Attack traffic reaching origin | 0.057% |
| Legitimate traffic challenged | 0.40% |
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 880 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
A brief increase in p99 latency of 231 ms during the first minute, then normal service.
Recommendations
- Review allow-listed partner ranges quarterly.
- Keep origin IPs out of public DNS history.
- Lower challenge thresholds on authentication endpoints during high-risk events.