Threat Bulletin 1164: UDP reflection (NTP) against a education platform platform in the Nordics

On Monday 11 August 2025 at 07:54 UTC, a UDP reflection (NTP) targeted a education platform customer in the Nordics. The attack peaked at 354.4 Gbps and lasted 189 minutes. Traffic originated from 2711 autonomous systems in 105 countries, predominantly residential proxy networks.

Vector UDP reflection (NTP)
Peak 354.4 Gbps
Duration 189 min
Time to mitigation 0.553 s
Attack traffic reaching origin 0.015%
Legitimate traffic challenged 0.74%

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 23 points of presence.

What the customer saw

The customer’s status page stayed green throughout; they learned about the attack from our notification.

Recommendations

  • Keep origin IPs out of public DNS history.
  • Enable authenticated origin pulls.
  • Enable log streaming to your SIEM for faster correlation.

11 thoughts on “Threat Bulletin 1164: UDP reflection (NTP) against a education platform platform in the Nordics”

  1. We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.

  2. We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.

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