On Saturday 13 September 2025 at 08:55 UTC, a ACK flood targeted a tax authority portal customer in Iberia. The attack peaked at 377.1 Gbps and lasted 134 minutes. Traffic originated from 453 autonomous systems in 17 countries, predominantly a Mirai-derived IoT botnet.
| Vector | ACK flood |
| Peak | 377.1 Gbps |
| Duration | 134 min |
| Time to mitigation | 0.801 s |
| Attack traffic reaching origin | 0.001% |
| Legitimate traffic challenged | 0.34% |
Timeline
The attack was preceded by an extortion email received two days earlier. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 31 points of presence.
What the customer saw
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Review allow-listed partner ranges quarterly.
- Enable authenticated origin pulls.
- Lower challenge thresholds on authentication endpoints during high-risk events.
Our auditors asked for exactly this kind of incident evidence under DORA.