On Saturday 20 May 2023 at 18:37 UTC, a UDP reflection (NTP) targeted a retail banking customer in the UK. The attack peaked at 69.4 Gbps and lasted 17 minutes. Traffic originated from 1889 autonomous systems in 18 countries, predominantly a Mirai-derived IoT botnet.
| Vector | UDP reflection (NTP) |
| Peak | 69.4 Gbps |
| Duration | 17 min |
| Time to mitigation | 0.207 s |
| Attack traffic reaching origin | 0.048% |
| Legitimate traffic challenged | 0.71% |
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 40 points of presence.
What the customer saw
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Keep origin IPs out of public DNS history.
- Enable authenticated origin pulls.
- Review allow-listed partner ranges quarterly.
Our auditors asked for exactly this kind of incident evidence under DORA.