On Sunday 10 March 2024 at 23:19 UTC, a ACK flood targeted a education platform customer in Iberia. The attack peaked at 303.0 Gbps and lasted 122 minutes. Traffic originated from 3851 autonomous systems in 53 countries, predominantly hijacked home routers.
| Vector | ACK flood |
| Peak | 303.0 Gbps |
| Duration | 122 min |
| Time to mitigation | 0.892 s |
| Attack traffic reaching origin | 0.036% |
| Legitimate traffic challenged | 0.68% |
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 24 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
- Review allow-listed partner ranges quarterly.
- Keep origin IPs out of public DNS history.
- Enable log streaming to your SIEM for faster correlation.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Thanks! Yes — the risk score and its components are included in every log record.
Would love a follow-up on how you handle HTTP/3 fingerprinting.
Machine-readable ranges are at /ips.json and via the API.
How do you avoid challenging uptime monitors and partners?
Great write-up. We saw almost the same pattern on our login endpoint last month.
Verified good bots and allow-listed partners bypass challenges entirely.
The point about origin IPs leaking through certificate transparency logs is underrated.
Machine-readable ranges are at /ips.json and via the API.
Thanks — sharing this with our on-call team.
Would love a follow-up on how you handle HTTP/3 fingerprinting.
The point about origin IPs leaking through certificate transparency logs is underrated.