On Monday 21 August 2023 at 22:48 UTC, a HTTP/2 rapid reset targeted a fashion retail customer in the Nordics. The attack peaked at 458.5 million requests per second and lasted 53 minutes. Traffic originated from 4198 autonomous systems in 15 countries, predominantly a headless-browser farm.
| Vector | HTTP/2 rapid reset |
| Peak | 458.5 million requests per second |
| Duration | 53 min |
| Time to mitigation | 0.091 s |
| Attack traffic reaching origin | 0.002% |
| Legitimate traffic challenged | 0.32% |
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 64 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
A brief increase in p99 latency of 51 ms during the first minute, then normal service.
Recommendations
- Enable log streaming to your SIEM for faster correlation.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Keep origin IPs out of public DNS history.
Could you share the dataset behind the percentages?
How do you avoid challenging uptime monitors and partners?
Carpet bombing is nasty. Good to see a clear explanation of it.
Solid runbook advice. The DNS-at-2am point hit home.