On Wednesday 27 October 2021 at 22:05 UTC, a WebSocket connection flood targeted a airline booking customer in the Middle East. The attack peaked at 674.8 million requests per second and lasted 31 minutes. Traffic originated from 2318 autonomous systems in 28 countries, predominantly compromised cloud VMs.
| Vector | WebSocket connection flood |
| Peak | 674.8 million requests per second |
| Duration | 31 min |
| Time to mitigation | 0.264 s |
| Attack traffic reaching origin | 0.004% |
| Legitimate traffic challenged | 0.65% |
Timeline
The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 43 within 33 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 93 ms during the first minute, then normal service.
Recommendations
- Enable log streaming to your SIEM for faster correlation.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.