On Saturday 18 June 2022 at 02:38 UTC, a Slowloris targeted a fashion retail customer in Western Europe. The attack peaked at 381.4 million requests per second and lasted 116 minutes. Traffic originated from 3342 autonomous systems in 86 countries, predominantly misconfigured open reflectors.
| Vector | Slowloris |
| Peak | 381.4 million requests per second |
| Duration | 116 min |
| Time to mitigation | 0.016 s |
| Attack traffic reaching origin | 0.029% |
| Legitimate traffic challenged | 0.18% |
Timeline
The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 498 within 33 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
- Review allow-listed partner ranges quarterly.
- Enable authenticated origin pulls.
- Enable log streaming to your SIEM for faster correlation.
Solid runbook advice. The DNS-at-2am point hit home.
Good question. We will cover that in a follow-up post.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Interesting that most attacks are under ten minutes. Our experience is similar.
The point about origin IPs leaking through certificate transparency logs is underrated.
Verified good bots and allow-listed partners bypass challenges entirely.
The billing model is what got our finance team on board, honestly.
Our auditors asked for exactly this kind of incident evidence under DORA.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
Nice to read a vendor blog that admits what went wrong.
Good question. We will cover that in a follow-up post.