On Monday 21 June 2021 at 16:59 UTC, a login endpoint flood targeted a online casino customer in the UK. The attack peaked at 71.1 million requests per second and lasted 25 minutes. Traffic originated from 1169 autonomous systems in 51 countries, predominantly a headless-browser farm.
| Vector | login endpoint flood |
| Peak | 71.1 million requests per second |
| Duration | 25 min |
| Time to mitigation | 0.346 s |
| Attack traffic reaching origin | 0.043% |
| Legitimate traffic challenged | 0.46% |
Timeline
The attack was preceded by a ransom note demanding payment in Monero. Request rates on the targeted routes exceeded their hourly baseline by a factor of 137 within 28 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
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Enable authenticated origin pulls.
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
Thanks — sharing this with our on-call team.
Nice to read a vendor blog that admits what went wrong.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Thanks! Yes — the risk score and its components are included in every log record.
Thanks — sharing this with our on-call team.
The point about origin IPs leaking through certificate transparency logs is underrated.