On Wednesday 30 November 2022 at 03:05 UTC, a cache-busting query flood targeted a healthcare portal customer in Central Europe. The attack peaked at 352.4 million requests per second and lasted 103 minutes. Traffic originated from 3270 autonomous systems in 19 countries, predominantly mobile carrier ranges.
| Vector | cache-busting query flood |
| Peak | 352.4 million requests per second |
| Duration | 103 min |
| Time to mitigation | 0.389 s |
| Attack traffic reaching origin | 0.075% |
| Legitimate traffic challenged | 0.18% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 570 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 157 ms during the first minute, then normal service.
Recommendations
- Keep origin IPs out of public DNS history.
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
Clear and practical, thanks.
Nice to read a vendor blog that admits what went wrong.
How do you avoid challenging uptime monitors and partners?
Thanks — sharing this with our on-call team.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Good question. We will cover that in a follow-up post.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?