On Tuesday 6 December 2022 at 16:52 UTC, a ACK flood targeted a online payments customer in the Nordics. The attack peaked at 207.2 Gbps and lasted 172 minutes. Traffic originated from 3067 autonomous systems in 62 countries, predominantly residential proxy networks.
| Vector | ACK flood |
| Peak | 207.2 Gbps |
| Duration | 172 min |
| Time to mitigation | 0.744 s |
| Attack traffic reaching origin | 0.012% |
| Legitimate traffic challenged | 0.43% |
Timeline
The attack was preceded by an extortion email received two days earlier. 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
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.
- Enable authenticated origin pulls.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Carpet bombing is nasty. Good to see a clear explanation of it.
Verified good bots and allow-listed partners bypass challenges entirely.
Is the risk score exposed in the logs so we can build our own dashboards on it?
We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.