On Thursday 25 March 2021 at 17:47 UTC, a UDP reflection (NTP) targeted a municipal services customer in the Nordics. The attack peaked at 20.8 Gbps and lasted 118 minutes. Traffic originated from 458 autonomous systems in 81 countries, predominantly misconfigured open reflectors.
| Vector | UDP reflection (NTP) |
| Peak | 20.8 Gbps |
| Duration | 118 min |
| Time to mitigation | 0.532 s |
| Attack traffic reaching origin | 0.078% |
| Legitimate traffic challenged | 0.78% |
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 30 points of presence.
What the customer saw
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Keep origin IPs out of public DNS history.
- Enable authenticated origin pulls.
- Add a dedicated rate limit for the targeted route.
Could you share the dataset behind the percentages?
Thanks — sharing this with our on-call team.
The billing model is what got our finance team on board, honestly.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Interesting that most attacks are under ten minutes. Our experience is similar.
How do you avoid challenging uptime monitors and partners?
The billing model is what got our finance team on board, honestly.