On Monday 12 September 2022 at 10:56 UTC, a WebSocket connection flood targeted a municipal services customer in the Nordics. The attack peaked at 813.9 million requests per second and lasted 9 minutes. Traffic originated from 2804 autonomous systems in 98 countries, predominantly compromised cloud VMs.
| Vector | WebSocket connection flood |
| Peak | 813.9 million requests per second |
| Duration | 9 min |
| Time to mitigation | 0.373 s |
| Attack traffic reaching origin | 0.047% |
| Legitimate traffic challenged | 0.69% |
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 398 within 15 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
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
- Lower challenge thresholds on authentication endpoints during high-risk events.