On Wednesday 17 July 2024 at 04:47 UTC, a Slowloris targeted a news publisher customer in the UK. The attack peaked at 200.4 million requests per second and lasted 160 minutes. Traffic originated from 1055 autonomous systems in 80 countries, predominantly a headless-browser farm.
| Vector | Slowloris |
| Peak | 200.4 million requests per second |
| Duration | 160 min |
| Time to mitigation | 0.372 s |
| Attack traffic reaching origin | 0.013% |
| Legitimate traffic challenged | 0.31% |
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 280 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
A brief increase in p99 latency of 60 ms during the first minute, then normal service.
Recommendations
- Enable authenticated origin pulls.
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
Is the risk score exposed in the logs so we can build our own dashboards on it?
We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.
Verified good bots and allow-listed partners bypass challenges entirely.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Do you publish the edge IP ranges in a machine-readable format?