On Sunday 26 October 2025 at 21:02 UTC, a ACK flood targeted a retail banking customer in the UK. The attack peaked at 65.8 Gbps and lasted 182 minutes. Traffic originated from 1139 autonomous systems in 6 countries, predominantly mobile carrier ranges.
| Vector | ACK flood |
| Peak | 65.8 Gbps |
| Duration | 182 min |
| Time to mitigation | 0.327 s |
| Attack traffic reaching origin | 0.002% |
| Legitimate traffic challenged | 0.39% |
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 31 points of presence.
What the customer saw
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Keep origin IPs out of public DNS history.
- Review allow-listed partner ranges quarterly.
- Enable authenticated origin pulls.