On Thursday 7 November 2024 at 08:00 UTC, a TLS handshake exhaustion targeted a B2B SaaS customer in Central Europe. The attack peaked at 31.2 million requests per second and lasted 140 minutes. Traffic originated from 2154 autonomous systems in 13 countries, predominantly a Mirai-derived IoT botnet.
| Vector | TLS handshake exhaustion |
| Peak | 31.2 million requests per second |
| Duration | 140 min |
| Time to mitigation | 0.519 s |
| Attack traffic reaching origin | 0.078% |
| Legitimate traffic challenged | 0.21% |
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 370 within 11 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 58 ms during the first minute, then normal service.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.