Threat Bulletin 0943: UDP reflection (DNS) against a tax authority portal platform in the UK

On Wednesday 9 October 2024 at 21:17 UTC, a UDP reflection (DNS) targeted a tax authority portal customer in the UK. The attack peaked at 313.5 Gbps and lasted 109 minutes. Traffic originated from 294 autonomous systems in 68 countries, predominantly hijacked home routers.

Vector UDP reflection (DNS)
Peak 313.5 Gbps
Duration 109 min
Time to mitigation 0.027 s
Attack traffic reaching origin 0.021%
Legitimate traffic challenged 0.49%

Timeline

The attack was preceded by a publicly announced sales event. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 17 points of presence.

What the customer saw

Checkout conversion was unchanged compared with the same hour of the previous week.

Recommendations

  • Review allow-listed partner ranges quarterly.
  • Enable log streaming to your SIEM for faster correlation.
  • Enable authenticated origin pulls.

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