On Sunday 18 April 2021 at 15:28 UTC, a HTTP GET flood targeted a healthcare portal customer in the Nordics. The attack peaked at 666.1 million requests per second and lasted 112 minutes. Traffic originated from 3843 autonomous systems in 42 countries, predominantly residential proxy networks.
| Vector | HTTP GET flood |
| Peak | 666.1 million requests per second |
| Duration | 112 min |
| Time to mitigation | 0.288 s |
| Attack traffic reaching origin | 0.013% |
| Legitimate traffic challenged | 0.15% |
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 350 within 12 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
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Keep origin IPs out of public DNS history.
- Enable authenticated origin pulls.
Our auditors asked for exactly this kind of incident evidence under DORA.
Clear and practical, thanks.
Carpet bombing is nasty. Good to see a clear explanation of it.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Thanks — sharing this with our on-call team.
Any plans to support per-tenant limits keyed on a JWT claim?
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?