Threat Bulletin 0694: carpet-bombing UDP flood against a tax authority portal platform in the Benelux

On Wednesday 25 October 2023 at 07:18 UTC, a carpet-bombing UDP flood targeted a tax authority portal customer in the Benelux. The attack peaked at 193.6 Gbps and lasted 164 minutes. Traffic originated from 2351 autonomous systems in 97 countries, predominantly residential proxy networks.

Vector carpet-bombing UDP flood
Peak 193.6 Gbps
Duration 164 min
Time to mitigation 0.835 s
Attack traffic reaching origin 0.056%
Legitimate traffic challenged 0.01%

Timeline

The attack was preceded by a breaking political story. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 13 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.
  • Enable log streaming to your SIEM for faster correlation.
  • Add a dedicated rate limit for the targeted route.

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