Threat Bulletin 1318: WebSocket connection flood against a developer platform platform in the Nordics

On Saturday 14 March 2026 at 02:21 UTC, a WebSocket connection flood targeted a developer platform customer in the Nordics. The attack peaked at 679.3 million requests per second and lasted 151 minutes. Traffic originated from 1782 autonomous systems in 45 countries, predominantly hijacked home routers.

Vector WebSocket connection flood
Peak 679.3 million requests per second
Duration 151 min
Time to mitigation 0.866 s
Attack traffic reaching origin 0.028%
Legitimate traffic challenged 0.24%

Timeline

The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 880 within 17 seconds. The risk score of participating clients crossed the challenge threshold automatically and proof-of-work difficulty rose with origin load.

What the customer saw

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

Recommendations

  • Review allow-listed partner ranges quarterly.
  • Add a dedicated rate limit for the targeted route.
  • Lower challenge thresholds on authentication endpoints during high-risk events.

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