On Wednesday 25 September 2024 at 03:50 UTC, a GRE flood targeted a developer platform customer in the Nordics. The attack peaked at 221.9 Gbps and lasted 172 minutes. Traffic originated from 3301 autonomous systems in 44 countries, predominantly hijacked home routers.
| Vector | GRE flood |
| Peak | 221.9 Gbps |
| Duration | 172 min |
| Time to mitigation | 0.323 s |
| Attack traffic reaching origin | 0.002% |
| Legitimate traffic challenged | 0.35% |
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 13 points of presence.
What the customer saw
A brief increase in p99 latency of 43 ms during the first minute, then normal service.
Recommendations
- Keep origin IPs out of public DNS history.
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
The point about origin IPs leaking through certificate transparency logs is underrated.