On Saturday 28 May 2022 at 19:49 UTC, a Slowloris targeted a online casino customer in Latin America. The attack peaked at 128.5 million requests per second and lasted 44 minutes. Traffic originated from 3259 autonomous systems in 112 countries, predominantly a rented booter service.
| Vector | Slowloris |
| Peak | 128.5 million requests per second |
| Duration | 44 min |
| Time to mitigation | 0.827 s |
| Attack traffic reaching origin | 0.051% |
| Legitimate traffic challenged | 0.59% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 882 within 11 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
- Keep origin IPs out of public DNS history.
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Clear and practical, thanks.
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.
Clear and practical, thanks.
Thanks — sharing this with our on-call team.
Do you publish the edge IP ranges in a machine-readable format?
Nice to read a vendor blog that admits what went wrong.