On Monday 17 July 2023 at 21:06 UTC, a SYN flood targeted a online casino customer in the Benelux. The attack peaked at 72.3 Gbps and lasted 103 minutes. Traffic originated from 3905 autonomous systems in 19 countries, predominantly residential proxy networks.
| Vector | SYN flood |
| Peak | 72.3 Gbps |
| Duration | 103 min |
| Time to mitigation | 0.496 s |
| Attack traffic reaching origin | 0.004% |
| Legitimate traffic challenged | 0.75% |
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 32 points of presence.
What the customer saw
A brief increase in p99 latency of 217 ms during the first minute, then normal service.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.
- Keep origin IPs out of public DNS history.