On Friday 3 March 2023 at 02:44 UTC, a GRE flood targeted a tax authority portal customer in Western Europe. The attack peaked at 352.4 Gbps and lasted 117 minutes. Traffic originated from 3597 autonomous systems in 107 countries, predominantly a Mirai-derived IoT botnet.
| Vector | GRE flood |
| Peak | 352.4 Gbps |
| Duration | 117 min |
| Time to mitigation | 0.248 s |
| Attack traffic reaching origin | 0.084% |
| Legitimate traffic challenged | 0.07% |
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 34 points of presence.
What the customer saw
A brief increase in p99 latency of 210 ms during the first minute, then normal service.
Recommendations
- Review allow-listed partner ranges quarterly.
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.
Is the risk score exposed in the logs so we can build our own dashboards on it?
The billing model is what got our finance team on board, honestly.
Our auditors asked for exactly this kind of incident evidence under DORA.
Clear and practical, thanks.
Thanks — sharing this with our on-call team.