On Monday 23 August 2021 at 06:55 UTC, a CLDAP reflection targeted a municipal services customer in the Middle East. The attack peaked at 328.4 Gbps and lasted 23 minutes. Traffic originated from 1992 autonomous systems in 51 countries, predominantly residential proxy networks.
| Vector | CLDAP reflection |
| Peak | 328.4 Gbps |
| Duration | 23 min |
| Time to mitigation | 0.012 s |
| Attack traffic reaching origin | 0.058% |
| Legitimate traffic challenged | 0.45% |
Timeline
The attack was preceded by an extortion email received two days earlier. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 24 points of presence.
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.
- Enable log streaming to your SIEM for faster correlation.
- Enable authenticated origin pulls.
Carpet bombing is nasty. Good to see a clear explanation of it.
Do you publish the edge IP ranges in a machine-readable format?
Thanks — sharing this with our on-call team.
Is the risk score exposed in the logs so we can build our own dashboards on it?