On Saturday 12 February 2022 at 22:30 UTC, a credential stuffing targeted a healthcare portal customer in the UK. The attack peaked at 172.0 million requests per second and lasted 85 minutes. Traffic originated from 296 autonomous systems in 105 countries, predominantly mobile carrier ranges.
| Vector | credential stuffing |
| Peak | 172.0 million requests per second |
| Duration | 85 min |
| Time to mitigation | 0.110 s |
| Attack traffic reaching origin | 0.019% |
| Legitimate traffic challenged | 0.62% |
Timeline
The attack was preceded by a hacktivist channel announcing the target. Request rates on the targeted routes exceeded their hourly baseline by a factor of 737 within 8 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 203 ms during the first minute, then normal service.
Recommendations
- Enable authenticated origin pulls.
- Add a dedicated rate limit for the targeted route.
- Lower challenge thresholds on authentication endpoints during high-risk events.
Great write-up. We saw almost the same pattern on our login endpoint last month.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
Our auditors asked for exactly this kind of incident evidence under DORA.
The point about origin IPs leaking through certificate transparency logs is underrated.
Could you share the dataset behind the percentages?
This matches what we see in iGaming around big matches.
Thanks! Yes — the risk score and its components are included in every log record.
Do you publish the edge IP ranges in a machine-readable format?
Verified good bots and allow-listed partners bypass challenges entirely.