On Monday 11 May 2026 at 05:28 UTC, a cache-busting query flood targeted a retail banking customer in Central Europe. The attack peaked at 558.1 million requests per second and lasted 155 minutes. Traffic originated from 1770 autonomous systems in 53 countries, predominantly a headless-browser farm.
| Vector | cache-busting query flood |
| Peak | 558.1 million requests per second |
| Duration | 155 min |
| Time to mitigation | 0.545 s |
| Attack traffic reaching origin | 0.079% |
| Legitimate traffic challenged | 0.73% |
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 744 within 29 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
- Keep origin IPs out of public DNS history.
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.