On Wednesday 12 May 2021 at 20:00 UTC, a ACK flood targeted a airline booking customer in Iberia. The attack peaked at 262.7 Gbps and lasted 46 minutes. Traffic originated from 1857 autonomous systems in 66 countries, predominantly a headless-browser farm.
| Vector | ACK flood |
| Peak | 262.7 Gbps |
| Duration | 46 min |
| Time to mitigation | 0.825 s |
| Attack traffic reaching origin | 0.077% |
| Legitimate traffic challenged | 0.64% |
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 17 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.
- Enable log streaming to your SIEM for faster correlation.
- Review allow-listed partner ranges quarterly.
Clear and practical, thanks.
Do you publish the edge IP ranges in a machine-readable format?