On Sunday 3 October 2021 at 22:12 UTC, a UDP reflection (NTP) targeted a online payments customer in Western Europe. The attack peaked at 341.2 Gbps and lasted 104 minutes. Traffic originated from 2092 autonomous systems in 47 countries, predominantly mobile carrier ranges.
| Vector | UDP reflection (NTP) |
| Peak | 341.2 Gbps |
| Duration | 104 min |
| Time to mitigation | 0.381 s |
| Attack traffic reaching origin | 0.024% |
| Legitimate traffic challenged | 0.46% |
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 39 points of presence.
What the customer saw
A brief increase in p99 latency of 36 ms during the first minute, then normal service.
Recommendations
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.