On Wednesday 15 March 2023 at 01:08 UTC, a UDP reflection (NTP) targeted a education platform customer in the UK. The attack peaked at 95.8 Gbps and lasted 45 minutes. Traffic originated from 1087 autonomous systems in 96 countries, predominantly compromised cloud VMs.
| Vector | UDP reflection (NTP) |
| Peak | 95.8 Gbps |
| Duration | 45 min |
| Time to mitigation | 0.722 s |
| Attack traffic reaching origin | 0.026% |
| Legitimate traffic challenged | 0.28% |
Timeline
The attack was preceded by an extortion email received two days earlier. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 20 points of presence.
What the customer saw
A brief increase in p99 latency of 116 ms during the first minute, then normal service.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable log streaming to your SIEM for faster correlation.
Interesting that most attacks are under ten minutes. Our experience is similar.
Great write-up. We saw almost the same pattern on our login endpoint last month.