On Saturday 17 July 2021 at 09:48 UTC, a credential stuffing targeted a online payments customer in Latin America. The attack peaked at 875.2 million requests per second and lasted 47 minutes. Traffic originated from 1803 autonomous systems in 26 countries, predominantly mobile carrier ranges.
| Vector | credential stuffing |
| Peak | 875.2 million requests per second |
| Duration | 47 min |
| Time to mitigation | 0.714 s |
| Attack traffic reaching origin | 0.038% |
| Legitimate traffic challenged | 0.17% |
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 514 within 22 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
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable log streaming to your SIEM for faster correlation.
- Keep origin IPs out of public DNS history.
Would love a follow-up on how you handle HTTP/3 fingerprinting.
Great to hear, thanks for sharing your experience.
Our auditors asked for exactly this kind of incident evidence under DORA.
Would love a follow-up on how you handle HTTP/3 fingerprinting.