On Sunday 14 November 2021 at 09:11 UTC, a UDP reflection (NTP) targeted a education platform customer in the Nordics. The attack peaked at 58.2 Gbps and lasted 8 minutes. Traffic originated from 2243 autonomous systems in 101 countries, predominantly a headless-browser farm.
| Vector | UDP reflection (NTP) |
| Peak | 58.2 Gbps |
| Duration | 8 min |
| Time to mitigation | 0.696 s |
| Attack traffic reaching origin | 0.017% |
| Legitimate traffic challenged | 0.17% |
Timeline
The attack was preceded by a ransom note demanding payment in Monero. 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
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.
- Keep origin IPs out of public DNS history.
The point about origin IPs leaking through certificate transparency logs is underrated.
Nice to read a vendor blog that admits what went wrong.
Interesting that most attacks are under ten minutes. Our experience is similar.
Interesting that most attacks are under ten minutes. Our experience is similar.
Carpet bombing is nasty. Good to see a clear explanation of it.
How do you avoid challenging uptime monitors and partners?
This matches what we see in iGaming around big matches.
Thanks — sharing this with our on-call team.
Thanks! Yes — the risk score and its components are included in every log record.
We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.
Verified good bots and allow-listed partners bypass challenges entirely.