On Friday 5 December 2025 at 19:53 UTC, a SYN flood targeted a tax authority portal customer in Iberia. The attack peaked at 159.8 Gbps and lasted 10 minutes. Traffic originated from 3820 autonomous systems in 15 countries, predominantly misconfigured open reflectors.
| Vector | SYN flood |
| Peak | 159.8 Gbps |
| Duration | 10 min |
| Time to mitigation | 0.563 s |
| Attack traffic reaching origin | 0.075% |
| Legitimate traffic challenged | 0.71% |
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 22 points of presence.
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.
- Enable authenticated origin pulls.