On Monday 13 May 2024 at 05:51 UTC, a Slowloris targeted a crypto exchange customer in the Benelux. The attack peaked at 834.4 million requests per second and lasted 45 minutes. Traffic originated from 2102 autonomous systems in 18 countries, predominantly a rented booter service.
| Vector | Slowloris |
| Peak | 834.4 million requests per second |
| Duration | 45 min |
| Time to mitigation | 0.415 s |
| Attack traffic reaching origin | 0.069% |
| Legitimate traffic challenged | 0.40% |
Timeline
The attack was preceded by a breaking political story. Request rates on the targeted routes exceeded their hourly baseline by a factor of 660 within 13 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.
- Add a dedicated rate limit for the targeted route.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Thanks — sharing this with our on-call team.
Verified good bots and allow-listed partners bypass challenges entirely.
Interesting that most attacks are under ten minutes. Our experience is similar.
Our auditors asked for exactly this kind of incident evidence under DORA.