On Thursday 1 July 2021 at 02:50 UTC, a SYN flood targeted a airline booking customer in North America. The attack peaked at 367.8 Gbps and lasted 58 minutes. Traffic originated from 798 autonomous systems in 98 countries, predominantly a headless-browser farm.
| Vector | SYN flood |
| Peak | 367.8 Gbps |
| Duration | 58 min |
| Time to mitigation | 0.431 s |
| Attack traffic reaching origin | 0.045% |
| Legitimate traffic challenged | 0.42% |
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 15 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 authenticated origin pulls.
- Add a dedicated rate limit for the targeted route.
The point about origin IPs leaking through certificate transparency logs is underrated.
Our auditors asked for exactly this kind of incident evidence under DORA.
Our auditors asked for exactly this kind of incident evidence under DORA.
Verified good bots and allow-listed partners bypass challenges entirely.
Our auditors asked for exactly this kind of incident evidence under DORA.
The point about origin IPs leaking through certificate transparency logs is underrated.
Verified good bots and allow-listed partners bypass challenges entirely.
Thanks — sharing this with our on-call team.
Interesting that most attacks are under ten minutes. Our experience is similar.