On Wednesday 5 May 2021 at 19:43 UTC, a GRE flood targeted a B2B SaaS customer in Iberia. The attack peaked at 46.5 Gbps and lasted 44 minutes. Traffic originated from 882 autonomous systems in 72 countries, predominantly compromised cloud VMs.
| Vector | GRE flood |
| Peak | 46.5 Gbps |
| Duration | 44 min |
| Time to mitigation | 0.119 s |
| Attack traffic reaching origin | 0.089% |
| Legitimate traffic challenged | 0.50% |
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 29 points of presence.
What the customer saw
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Good question. We will cover that in a follow-up post.
Could you share the dataset behind the percentages?