On Sunday 28 September 2025 at 08:17 UTC, a SYN flood targeted a online casino customer in the Benelux. The attack peaked at 309.4 Gbps and lasted 104 minutes. Traffic originated from 3676 autonomous systems in 99 countries, predominantly a headless-browser farm.
| Vector | SYN flood |
| Peak | 309.4 Gbps |
| Duration | 104 min |
| Time to mitigation | 0.164 s |
| Attack traffic reaching origin | 0.072% |
| Legitimate traffic challenged | 0.23% |
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 21 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
- Enable log streaming to your SIEM for faster correlation.
- Review allow-listed partner ranges quarterly.
- Add a dedicated rate limit for the targeted route.