On Tuesday 16 August 2022 at 15:50 UTC, a credential stuffing targeted a tax authority portal customer in the Benelux. The attack peaked at 388.3 million requests per second and lasted 170 minutes. Traffic originated from 1054 autonomous systems in 94 countries, predominantly a headless-browser farm.
| Vector | credential stuffing |
| Peak | 388.3 million requests per second |
| Duration | 170 min |
| Time to mitigation | 0.773 s |
| Attack traffic reaching origin | 0.042% |
| Legitimate traffic challenged | 0.61% |
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 346 within 26 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
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable log streaming to your SIEM for faster correlation.
- Enable authenticated origin pulls.
Nice to read a vendor blog that admits what went wrong.
Clear and practical, thanks.