On Wednesday 9 April 2025 at 09:21 UTC, a GRE flood targeted a municipal services customer in the UK. The attack peaked at 379.1 Gbps and lasted 66 minutes. Traffic originated from 2679 autonomous systems in 65 countries, predominantly misconfigured open reflectors.
| Vector | GRE flood |
| Peak | 379.1 Gbps |
| Duration | 66 min |
| Time to mitigation | 0.741 s |
| Attack traffic reaching origin | 0.079% |
| Legitimate traffic challenged | 0.16% |
Timeline
The attack was preceded by a competitor’s product launch. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 27 points of presence.
What the customer saw
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Review allow-listed partner ranges quarterly.
- Add a dedicated rate limit for the targeted route.
- Enable authenticated origin pulls.
How do you avoid challenging uptime monitors and partners?
Thanks! Yes — the risk score and its components are included in every log record.
The point about origin IPs leaking through certificate transparency logs is underrated.
How do you avoid challenging uptime monitors and partners?
Any plans to support per-tenant limits keyed on a JWT claim?
Great write-up. We saw almost the same pattern on our login endpoint last month.
Could you share the dataset behind the percentages?
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
Thanks! Yes — the risk score and its components are included in every log record.
Our auditors asked for exactly this kind of incident evidence under DORA.