On Wednesday 14 July 2021 at 05:24 UTC, a Slowloris targeted a developer platform customer in Iberia. The attack peaked at 86.6 million requests per second and lasted 162 minutes. Traffic originated from 269 autonomous systems in 71 countries, predominantly misconfigured open reflectors.
| Vector | Slowloris |
| Peak | 86.6 million requests per second |
| Duration | 162 min |
| Time to mitigation | 0.113 s |
| Attack traffic reaching origin | 0.006% |
| Legitimate traffic challenged | 0.72% |
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 383 within 27 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
- Review allow-listed partner ranges quarterly.
- Enable authenticated origin pulls.
- Lower challenge thresholds on authentication endpoints during high-risk events.