On Thursday 9 December 2021 at 00:06 UTC, a credential stuffing targeted a municipal services customer in North America. The attack peaked at 627.6 million requests per second and lasted 104 minutes. Traffic originated from 3924 autonomous systems in 115 countries, predominantly residential proxy networks.
| Vector | credential stuffing |
| Peak | 627.6 million requests per second |
| Duration | 104 min |
| Time to mitigation | 0.823 s |
| Attack traffic reaching origin | 0.068% |
| Legitimate traffic challenged | 0.11% |
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 667 within 40 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
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.