On Sunday 10 September 2023 at 16:59 UTC, a credential stuffing targeted a news publisher customer in the UK. The attack peaked at 865.9 million requests per second and lasted 187 minutes. Traffic originated from 1626 autonomous systems in 109 countries, predominantly a headless-browser farm.
| Vector | credential stuffing |
| Peak | 865.9 million requests per second |
| Duration | 187 min |
| Time to mitigation | 0.706 s |
| Attack traffic reaching origin | 0.018% |
| Legitimate traffic challenged | 0.03% |
Timeline
The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 609 within 36 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
A brief increase in p99 latency of 24 ms during the first minute, then normal service.
Recommendations
- Review allow-listed partner ranges quarterly.
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.