On Tuesday 14 December 2021 at 17:37 UTC, a credential stuffing targeted a education platform customer in Southeast Asia. The attack peaked at 972.4 million requests per second and lasted 154 minutes. Traffic originated from 1122 autonomous systems in 52 countries, predominantly a rented booter service.
| Vector | credential stuffing |
| Peak | 972.4 million requests per second |
| Duration | 154 min |
| Time to mitigation | 0.259 s |
| Attack traffic reaching origin | 0.082% |
| Legitimate traffic challenged | 0.59% |
Timeline
The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 493 within 37 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
- Enable authenticated origin pulls.
- Add a dedicated rate limit for the targeted route.
- Enable log streaming to your SIEM for faster correlation.
Our auditors asked for exactly this kind of incident evidence under DORA.
Solid runbook advice. The DNS-at-2am point hit home.
Carpet bombing is nasty. Good to see a clear explanation of it.
How do you avoid challenging uptime monitors and partners?
Good question. We will cover that in a follow-up post.
Clear and practical, thanks.
Thanks! Yes — the risk score and its components are included in every log record.