On Tuesday 31 January 2023 at 22:20 UTC, a credential stuffing targeted a B2B SaaS customer in the Nordics. The attack peaked at 367.3 million requests per second and lasted 145 minutes. Traffic originated from 923 autonomous systems in 19 countries, predominantly a Mirai-derived IoT botnet.
| Vector | credential stuffing |
| Peak | 367.3 million requests per second |
| Duration | 145 min |
| Time to mitigation | 0.560 s |
| Attack traffic reaching origin | 0.005% |
| Legitimate traffic challenged | 0.11% |
Timeline
The attack was preceded by a hacktivist channel announcing the target. Request rates on the targeted routes exceeded their hourly baseline by a factor of 352 within 9 seconds. The risk score of participating clients crossed the challenge threshold automatically and proof-of-work difficulty rose with origin load.
What the customer saw
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Keep origin IPs out of public DNS history.
- Enable authenticated origin pulls.
Thanks — sharing this with our on-call team.