On Monday 25 October 2021 at 14:41 UTC, a UDP reflection (NTP) targeted a tax authority portal customer in Central Europe. The attack peaked at 24.2 Gbps and lasted 122 minutes. Traffic originated from 4196 autonomous systems in 114 countries, predominantly compromised cloud VMs.
| Vector | UDP reflection (NTP) |
| Peak | 24.2 Gbps |
| Duration | 122 min |
| Time to mitigation | 0.203 s |
| Attack traffic reaching origin | 0.029% |
| Legitimate traffic challenged | 0.16% |
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 28 points of presence.
What the customer saw
The customer’s status page stayed green throughout; they learned about the attack from our notification.
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.