On Friday 26 November 2021 at 12:30 UTC, a UDP reflection (DNS) targeted a B2B SaaS customer in North America. The attack peaked at 228.8 Gbps and lasted 85 minutes. Traffic originated from 154 autonomous systems in 47 countries, predominantly compromised cloud VMs.
| Vector | UDP reflection (DNS) |
| Peak | 228.8 Gbps |
| Duration | 85 min |
| Time to mitigation | 0.896 s |
| Attack traffic reaching origin | 0.061% |
| Legitimate traffic challenged | 0.71% |
Timeline
The attack was preceded by a breaking political story. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 38 points of presence.
What the customer saw
A brief increase in p99 latency of 214 ms during the first minute, then normal service.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Keep origin IPs out of public DNS history.
- Enable authenticated origin pulls.