Threat Bulletin 0558: WebSocket connection flood against a gaming community platform in Central Europe

On Thursday 13 April 2023 at 19:53 UTC, a WebSocket connection flood targeted a gaming community customer in Central Europe. The attack peaked at 735.6 million requests per second and lasted 182 minutes. Traffic originated from 3148 autonomous systems in 37 countries, predominantly residential proxy networks.

Vector WebSocket connection flood
Peak 735.6 million requests per second
Duration 182 min
Time to mitigation 0.534 s
Attack traffic reaching origin 0.002%
Legitimate traffic challenged 0.37%

Timeline

The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 208 within 24 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

No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.

Recommendations

  • Keep origin IPs out of public DNS history.
  • Review allow-listed partner ranges quarterly.
  • Add a dedicated rate limit for the targeted route.

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