On Thursday 13 May 2021 at 21:36 UTC, a carpet-bombing UDP flood targeted a tax authority portal customer in Central Europe. The attack peaked at 96.7 Gbps and lasted 47 minutes. Traffic originated from 3652 autonomous systems in 98 countries, predominantly a headless-browser farm.
| Vector | carpet-bombing UDP flood |
| Peak | 96.7 Gbps |
| Duration | 47 min |
| Time to mitigation | 0.041 s |
| Attack traffic reaching origin | 0.001% |
| Legitimate traffic challenged | 0.58% |
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 21 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.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Add a dedicated rate limit for the targeted route.