On Friday 15 April 2022 at 10:12 UTC, a cache-busting query flood targeted a tax authority portal customer in the Middle East. The attack peaked at 201.6 million requests per second and lasted 181 minutes. Traffic originated from 3079 autonomous systems in 61 countries, predominantly mobile carrier ranges.
| Vector | cache-busting query flood |
| Peak | 201.6 million requests per second |
| Duration | 181 min |
| Time to mitigation | 0.222 s |
| Attack traffic reaching origin | 0.077% |
| Legitimate traffic challenged | 0.28% |
Timeline
The attack was preceded by a breaking political story. Request rates on the targeted routes exceeded their hourly baseline by a factor of 851 within 18 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 194 ms during the first minute, then normal service.
Recommendations
- Enable log streaming to your SIEM for faster correlation.
- Review allow-listed partner ranges quarterly.
- Lower challenge thresholds on authentication endpoints during high-risk events.
Could you share the dataset behind the percentages?
Verified good bots and allow-listed partners bypass challenges entirely.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
Great write-up. We saw almost the same pattern on our login endpoint last month.
Is the risk score exposed in the logs so we can build our own dashboards on it?
Our auditors asked for exactly this kind of incident evidence under DORA.