On Thursday 22 July 2021 at 19:05 UTC, a Slowloris targeted a sports betting customer in Latin America. The attack peaked at 164.7 million requests per second and lasted 86 minutes. Traffic originated from 1441 autonomous systems in 17 countries, predominantly compromised cloud VMs.
| Vector | Slowloris |
| Peak | 164.7 million requests per second |
| Duration | 86 min |
| Time to mitigation | 0.161 s |
| Attack traffic reaching origin | 0.087% |
| Legitimate traffic challenged | 0.59% |
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 479 within 35 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
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Keep origin IPs out of public DNS history.
- Enable log streaming to your SIEM for faster correlation.