On Monday 26 June 2023 at 21:41 UTC, a WebSocket connection flood targeted a healthcare portal customer in North America. The attack peaked at 631.6 million requests per second and lasted 163 minutes. Traffic originated from 493 autonomous systems in 52 countries, predominantly misconfigured open reflectors.
| Vector | WebSocket connection flood |
| Peak | 631.6 million requests per second |
| Duration | 163 min |
| Time to mitigation | 0.087 s |
| Attack traffic reaching origin | 0.031% |
| Legitimate traffic challenged | 0.56% |
Timeline
The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 299 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
- Enable authenticated origin pulls.
- Enable log streaming to your SIEM for faster correlation.
- 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.
Thanks! Yes — the risk score and its components are included in every log record.
Solid runbook advice. The DNS-at-2am point hit home.
The billing model is what got our finance team on board, honestly.
Thanks! Yes — the risk score and its components are included in every log record.
How do you avoid challenging uptime monitors and partners?
Thanks — sharing this with our on-call team.