On Friday 8 September 2023 at 23:19 UTC, a SYN flood targeted a municipal services customer in the UK. The attack peaked at 67.3 Gbps and lasted 99 minutes. Traffic originated from 2253 autonomous systems in 32 countries, predominantly a Mirai-derived IoT botnet.
| Vector | SYN flood |
| Peak | 67.3 Gbps |
| Duration | 99 min |
| Time to mitigation | 0.673 s |
| Attack traffic reaching origin | 0.046% |
| Legitimate traffic challenged | 0.28% |
Timeline
The attack was preceded by a breaking political story. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 15 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.
- Review allow-listed partner ranges quarterly.
- Add a dedicated rate limit for the targeted route.