On Saturday 23 March 2024 at 19:28 UTC, a cache-busting query flood targeted a retail banking customer in the Benelux. The attack peaked at 336.5 million requests per second and lasted 13 minutes. Traffic originated from 3915 autonomous systems in 56 countries, predominantly residential proxy networks.
| Vector | cache-busting query flood |
| Peak | 336.5 million requests per second |
| Duration | 13 min |
| Time to mitigation | 0.203 s |
| Attack traffic reaching origin | 0.013% |
| Legitimate traffic challenged | 0.17% |
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 855 within 35 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 log streaming to your SIEM for faster correlation.
- Enable authenticated origin pulls.
- Keep origin IPs out of public DNS history.
Clear and practical, thanks.