On Thursday 29 July 2021 at 14:45 UTC, a GRE flood targeted a news publisher customer in the Nordics. The attack peaked at 298.5 Gbps and lasted 79 minutes. Traffic originated from 2066 autonomous systems in 89 countries, predominantly misconfigured open reflectors.
| Vector | GRE flood |
| Peak | 298.5 Gbps |
| Duration | 79 min |
| Time to mitigation | 0.746 s |
| Attack traffic reaching origin | 0.071% |
| Legitimate traffic challenged | 0.47% |
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 37 points of presence.
What the customer saw
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Enable log streaming to your SIEM for faster correlation.
- Keep origin IPs out of public DNS history.
- Add a dedicated rate limit for the targeted route.