On Sunday 3 April 2022 at 04:04 UTC, a ACK flood targeted a B2B SaaS customer in the UK. The attack peaked at 167.2 Gbps and lasted 37 minutes. Traffic originated from 2954 autonomous systems in 110 countries, predominantly a headless-browser farm.
| Vector | ACK flood |
| Peak | 167.2 Gbps |
| Duration | 37 min |
| Time to mitigation | 0.315 s |
| Attack traffic reaching origin | 0.054% |
| Legitimate traffic challenged | 0.72% |
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 29 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.
- Keep origin IPs out of public DNS history.