On Saturday 17 June 2023 at 23:42 UTC, a CLDAP reflection targeted a crypto exchange customer in the UK. The attack peaked at 34.1 Gbps and lasted 18 minutes. Traffic originated from 2930 autonomous systems in 15 countries, predominantly compromised cloud VMs.
| Vector | CLDAP reflection |
| Peak | 34.1 Gbps |
| Duration | 18 min |
| Time to mitigation | 0.694 s |
| Attack traffic reaching origin | 0.062% |
| Legitimate traffic challenged | 0.62% |
Timeline
The attack was preceded by a ransom note demanding payment in Monero. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 33 points of presence.
What the customer saw
A brief increase in p99 latency of 197 ms during the first minute, then normal service.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.
Would love a follow-up on how you handle HTTP/3 fingerprinting.
Nice to read a vendor blog that admits what went wrong.
Clear and practical, thanks.
Great write-up. We saw almost the same pattern on our login endpoint last month.
Machine-readable ranges are at /ips.json and via the API.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.