On Wednesday 4 June 2025 at 17:30 UTC, a Slowloris targeted a electronics retail customer in the Benelux. The attack peaked at 742.3 million requests per second and lasted 43 minutes. Traffic originated from 1183 autonomous systems in 89 countries, predominantly compromised cloud VMs.
| Vector | Slowloris |
| Peak | 742.3 million requests per second |
| Duration | 43 min |
| Time to mitigation | 0.049 s |
| Attack traffic reaching origin | 0.059% |
| Legitimate traffic challenged | 0.53% |
Timeline
The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 173 within 17 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
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.
- Lower challenge thresholds on authentication endpoints during high-risk events.
Any plans to support per-tenant limits keyed on a JWT claim?
Solid runbook advice. The DNS-at-2am point hit home.
Would love a follow-up on how you handle HTTP/3 fingerprinting.
Could you share the dataset behind the percentages?