On Wednesday 1 November 2023 at 13:16 UTC, a Slowloris targeted a fashion retail customer in Latin America. The attack peaked at 244.0 million requests per second and lasted 162 minutes. Traffic originated from 2394 autonomous systems in 79 countries, predominantly a Mirai-derived IoT botnet.
| Vector | Slowloris |
| Peak | 244.0 million requests per second |
| Duration | 162 min |
| Time to mitigation | 0.254 s |
| Attack traffic reaching origin | 0.090% |
| Legitimate traffic challenged | 0.16% |
Timeline
The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 658 within 35 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
- Keep origin IPs out of public DNS history.
- Review allow-listed partner ranges quarterly.
- Lower challenge thresholds on authentication endpoints during high-risk events.
Carpet bombing is nasty. Good to see a clear explanation of it.
The point about origin IPs leaking through certificate transparency logs is underrated.