On Sunday 20 August 2023 at 09:00 UTC, a CLDAP reflection targeted a tax authority portal customer in Western Europe. The attack peaked at 32.3 Gbps and lasted 173 minutes. Traffic originated from 2718 autonomous systems in 58 countries, predominantly mobile carrier ranges.
| Vector | CLDAP reflection |
| Peak | 32.3 Gbps |
| Duration | 173 min |
| Time to mitigation | 0.444 s |
| Attack traffic reaching origin | 0.035% |
| Legitimate traffic challenged | 0.35% |
Timeline
The attack was preceded by no stated motive. 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
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.
- Add a dedicated rate limit for the targeted route.
- Review allow-listed partner ranges quarterly.