On Sunday 30 March 2025 at 19:40 UTC, a TLS handshake exhaustion targeted a video streaming customer in North America. The attack peaked at 960.7 million requests per second and lasted 34 minutes. Traffic originated from 2895 autonomous systems in 29 countries, predominantly a headless-browser farm.
| Vector | TLS handshake exhaustion |
| Peak | 960.7 million requests per second |
| Duration | 34 min |
| Time to mitigation | 0.814 s |
| Attack traffic reaching origin | 0.048% |
| Legitimate traffic challenged | 0.07% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 834 within 29 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
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.
Our auditors asked for exactly this kind of incident evidence under DORA.
The billing model is what got our finance team on board, honestly.
Good question. We will cover that in a follow-up post.