On Tuesday 20 September 2022 at 22:10 UTC, a HTTP GET flood targeted a electronics retail customer in the UK. The attack peaked at 673.6 million requests per second and lasted 38 minutes. Traffic originated from 2398 autonomous systems in 38 countries, predominantly hijacked home routers.
| Vector | HTTP GET flood |
| Peak | 673.6 million requests per second |
| Duration | 38 min |
| Time to mitigation | 0.678 s |
| Attack traffic reaching origin | 0.068% |
| Legitimate traffic challenged | 0.42% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 85 within 38 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 93 ms during the first minute, then normal service.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.
- Keep origin IPs out of public DNS history.
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.
We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.