On Wednesday 1 September 2021 at 03:14 UTC, a GRE flood targeted a B2B SaaS customer in the Nordics. The attack peaked at 315.6 Gbps and lasted 92 minutes. Traffic originated from 1232 autonomous systems in 118 countries, predominantly mobile carrier ranges.
| Vector | GRE flood |
| Peak | 315.6 Gbps |
| Duration | 92 min |
| Time to mitigation | 0.898 s |
| Attack traffic reaching origin | 0.089% |
| Legitimate traffic challenged | 0.54% |
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 25 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 log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
Would love a follow-up on how you handle HTTP/3 fingerprinting.