On Friday 5 November 2021 at 05:09 UTC, a UDP reflection (DNS) targeted a tax authority portal customer in Iberia. The attack peaked at 368.4 Gbps and lasted 20 minutes. Traffic originated from 2791 autonomous systems in 108 countries, predominantly a rented booter service.
| Vector | UDP reflection (DNS) |
| Peak | 368.4 Gbps |
| Duration | 20 min |
| Time to mitigation | 0.807 s |
| Attack traffic reaching origin | 0.021% |
| Legitimate traffic challenged | 0.18% |
Timeline
The attack was preceded by a publicly announced sales event. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 14 points of presence.
What the customer saw
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Keep origin IPs out of public DNS history.
- Enable log streaming to your SIEM for faster correlation.