On Wednesday 25 May 2022 at 21:19 UTC, a UDP reflection (DNS) targeted a retail banking customer in Western Europe. The attack peaked at 253.2 Gbps and lasted 114 minutes. Traffic originated from 373 autonomous systems in 82 countries, predominantly compromised cloud VMs.
| Vector | UDP reflection (DNS) |
| Peak | 253.2 Gbps |
| Duration | 114 min |
| Time to mitigation | 0.770 s |
| Attack traffic reaching origin | 0.043% |
| Legitimate traffic challenged | 0.44% |
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 29 points of presence.
What the customer saw
A brief increase in p99 latency of 46 ms during the first minute, then normal service.
Recommendations
- Keep origin IPs out of public DNS history.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.