On Tuesday 6 April 2021 at 23:59 UTC, a Slowloris targeted a crypto exchange customer in Latin America. The attack peaked at 60.9 million requests per second and lasted 165 minutes. Traffic originated from 1112 autonomous systems in 51 countries, predominantly mobile carrier ranges.
| Vector | Slowloris |
| Peak | 60.9 million requests per second |
| Duration | 165 min |
| Time to mitigation | 0.372 s |
| Attack traffic reaching origin | 0.040% |
| Legitimate traffic challenged | 0.01% |
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 592 within 30 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
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable authenticated origin pulls.
- Add a dedicated rate limit for the targeted route.