On Wednesday 6 December 2023 at 08:36 UTC, a SYN flood targeted a online payments customer in North America. The attack peaked at 373.5 Gbps and lasted 24 minutes. Traffic originated from 2113 autonomous systems in 115 countries, predominantly residential proxy networks.
| Vector | SYN flood |
| Peak | 373.5 Gbps |
| Duration | 24 min |
| Time to mitigation | 0.496 s |
| Attack traffic reaching origin | 0.033% |
| Legitimate traffic challenged | 0.50% |
Timeline
The attack was preceded by no stated motive. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 13 points of presence.
What the customer saw
A brief increase in p99 latency of 136 ms during the first minute, then normal service.
Recommendations
- Keep origin IPs out of public DNS history.
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
The billing model is what got our finance team on board, honestly.
Great to hear, thanks for sharing your experience.
Any plans to support per-tenant limits keyed on a JWT claim?
Thanks! Yes — the risk score and its components are included in every log record.
Carpet bombing is nasty. Good to see a clear explanation of it.
Great write-up. We saw almost the same pattern on our login endpoint last month.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
Solid runbook advice. The DNS-at-2am point hit home.
Solid runbook advice. The DNS-at-2am point hit home.
The billing model is what got our finance team on board, honestly.
Nice to read a vendor blog that admits what went wrong.