On Saturday 14 October 2023 at 01:09 UTC, a login endpoint flood targeted a online casino customer in Central Europe. The attack peaked at 594.9 million requests per second and lasted 117 minutes. Traffic originated from 3553 autonomous systems in 111 countries, predominantly residential proxy networks.
| Vector | login endpoint flood |
| Peak | 594.9 million requests per second |
| Duration | 117 min |
| Time to mitigation | 0.932 s |
| Attack traffic reaching origin | 0.060% |
| Legitimate traffic challenged | 0.80% |
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 270 within 13 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 109 ms during the first minute, then normal service.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
The point about origin IPs leaking through certificate transparency logs is underrated.
Great write-up. We saw almost the same pattern on our login endpoint last month.