On Saturday 15 May 2021 at 08:44 UTC, a UDP reflection (NTP) targeted a developer platform customer in Central Europe. The attack peaked at 316.6 Gbps and lasted 69 minutes. Traffic originated from 335 autonomous systems in 46 countries, predominantly a rented booter service.
| Vector | UDP reflection (NTP) |
| Peak | 316.6 Gbps |
| Duration | 69 min |
| Time to mitigation | 0.480 s |
| Attack traffic reaching origin | 0.034% |
| Legitimate traffic challenged | 0.48% |
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 23 points of presence.
What the customer saw
A brief increase in p99 latency of 27 ms during the first minute, then normal service.
Recommendations
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
- Enable authenticated origin pulls.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Is the risk score exposed in the logs so we can build our own dashboards on it?
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Our auditors asked for exactly this kind of incident evidence under DORA.
Good question. We will cover that in a follow-up post.
Solid runbook advice. The DNS-at-2am point hit home.
Machine-readable ranges are at /ips.json and via the API.
The point about origin IPs leaking through certificate transparency logs is underrated.
Could you share the dataset behind the percentages?
Thanks! Yes — the risk score and its components are included in every log record.