On Sunday 18 July 2021 at 11:25 UTC, a search endpoint flood targeted a electronics retail customer in the Nordics. The attack peaked at 273.8 million requests per second and lasted 23 minutes. Traffic originated from 4177 autonomous systems in 27 countries, predominantly a headless-browser farm.
| Vector | search endpoint flood |
| Peak | 273.8 million requests per second |
| Duration | 23 min |
| Time to mitigation | 0.406 s |
| Attack traffic reaching origin | 0.090% |
| Legitimate traffic challenged | 0.15% |
Timeline
The attack was preceded by a ransom note demanding payment in Monero. Request rates on the targeted routes exceeded their hourly baseline by a factor of 121 within 31 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
- Enable authenticated origin pulls.
- Enable log streaming to your SIEM for faster correlation.
- Review allow-listed partner ranges quarterly.
The point about origin IPs leaking through certificate transparency logs is underrated.
We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Nice to read a vendor blog that admits what went wrong.
Thanks — sharing this with our on-call team.
Clear and practical, thanks.
Thanks! Yes — the risk score and its components are included in every log record.