On Friday 5 March 2021 at 18:56 UTC, a Slowloris targeted a airline booking customer in Western Europe. The attack peaked at 764.2 million requests per second and lasted 31 minutes. Traffic originated from 1589 autonomous systems in 36 countries, predominantly residential proxy networks.
| Vector | Slowloris |
| Peak | 764.2 million requests per second |
| Duration | 31 min |
| Time to mitigation | 0.102 s |
| Attack traffic reaching origin | 0.076% |
| Legitimate traffic challenged | 0.66% |
Timeline
The attack was preceded by a ransom note demanding payment in Monero. Request rates on the targeted routes exceeded their hourly baseline by a factor of 780 within 39 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 59 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.
- Add a dedicated rate limit for the targeted route.