On Tuesday 16 November 2021 at 19:40 UTC, a Slowloris targeted a fashion retail customer in North America. The attack peaked at 549.6 million requests per second and lasted 148 minutes. Traffic originated from 1140 autonomous systems in 6 countries, predominantly mobile carrier ranges.
| Vector | Slowloris |
| Peak | 549.6 million requests per second |
| Duration | 148 min |
| Time to mitigation | 0.304 s |
| Attack traffic reaching origin | 0.008% |
| Legitimate traffic challenged | 0.09% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 371 within 12 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
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Review allow-listed partner ranges quarterly.
- Enable authenticated origin pulls.
- Lower challenge thresholds on authentication endpoints during high-risk events.