On Tuesday 14 June 2022 at 03:42 UTC, a Slowloris targeted a tax authority portal customer in the Middle East. The attack peaked at 323.6 million requests per second and lasted 94 minutes. Traffic originated from 3289 autonomous systems in 102 countries, predominantly mobile carrier ranges.
| Vector | Slowloris |
| Peak | 323.6 million requests per second |
| Duration | 94 min |
| Time to mitigation | 0.558 s |
| Attack traffic reaching origin | 0.060% |
| Legitimate traffic challenged | 0.49% |
Timeline
The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 505 within 40 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.
- Review allow-listed partner ranges quarterly.
- Add a dedicated rate limit for the targeted route.
How do you avoid challenging uptime monitors and partners?
Interesting that most attacks are under ten minutes. Our experience is similar.
Thanks! Yes — the risk score and its components are included in every log record.