On Friday 21 July 2023 at 03:02 UTC, a SYN flood targeted a B2B SaaS customer in the UK. The attack peaked at 192.7 Gbps and lasted 156 minutes. Traffic originated from 1304 autonomous systems in 54 countries, predominantly residential proxy networks.
| Vector | SYN flood |
| Peak | 192.7 Gbps |
| Duration | 156 min |
| Time to mitigation | 0.174 s |
| Attack traffic reaching origin | 0.068% |
| Legitimate traffic challenged | 0.27% |
Timeline
The attack was preceded by a breaking political story. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 16 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.
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
Great write-up. We saw almost the same pattern on our login endpoint last month.
Great to hear, thanks for sharing your experience.