On Tuesday 23 January 2024 at 17:24 UTC, a search endpoint flood targeted a retail banking customer in North America. The attack peaked at 413.0 million requests per second and lasted 8 minutes. Traffic originated from 481 autonomous systems in 72 countries, predominantly misconfigured open reflectors.
| Vector | search endpoint flood |
| Peak | 413.0 million requests per second |
| Duration | 8 min |
| Time to mitigation | 0.776 s |
| Attack traffic reaching origin | 0.053% |
| Legitimate traffic challenged | 0.53% |
Timeline
The attack was preceded by a hacktivist channel announcing the target. Request rates on the targeted routes exceeded their hourly baseline by a factor of 140 within 40 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
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable authenticated origin pulls.
- Add a dedicated rate limit for the targeted route.
The point about origin IPs leaking through certificate transparency logs is underrated.
Verified good bots and allow-listed partners bypass challenges entirely.
Nice to read a vendor blog that admits what went wrong.
Verified good bots and allow-listed partners bypass challenges entirely.
Would love a follow-up on how you handle HTTP/3 fingerprinting.