On Sunday 5 March 2023 at 13:47 UTC, a SYN flood targeted a B2B SaaS customer in Southeast Asia. The attack peaked at 255.6 Gbps and lasted 42 minutes. Traffic originated from 4165 autonomous systems in 104 countries, predominantly a rented booter service.
| Vector | SYN flood |
| Peak | 255.6 Gbps |
| Duration | 42 min |
| Time to mitigation | 0.074 s |
| Attack traffic reaching origin | 0.002% |
| Legitimate traffic challenged | 0.40% |
Timeline
The attack was preceded by a publicly announced sales event. 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
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.
- Enable authenticated origin pulls.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Interesting that most attacks are under ten minutes. Our experience is similar.
Interesting that most attacks are under ten minutes. Our experience is similar.
Great to hear, thanks for sharing your experience.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Solid runbook advice. The DNS-at-2am point hit home.
Would love a follow-up on how you handle HTTP/3 fingerprinting.
Nice to read a vendor blog that admits what went wrong.