On Friday 23 April 2021 at 05:56 UTC, a UDP reflection (DNS) targeted a retail banking customer in Latin America. The attack peaked at 225.7 Gbps and lasted 26 minutes. Traffic originated from 2871 autonomous systems in 77 countries, predominantly a Mirai-derived IoT botnet.
| Vector | UDP reflection (DNS) |
| Peak | 225.7 Gbps |
| Duration | 26 min |
| Time to mitigation | 0.752 s |
| Attack traffic reaching origin | 0.018% |
| Legitimate traffic challenged | 0.46% |
Timeline
The attack was preceded by a publicly announced sales event. 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
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Keep origin IPs out of public DNS history.
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.
Great write-up. We saw almost the same pattern on our login endpoint last month.