Threat Bulletin 1133: WebSocket connection flood against a airline booking platform in North America

On Monday 30 June 2025 at 13:15 UTC, a WebSocket connection flood targeted a airline booking customer in North America. The attack peaked at 790.7 million requests per second and lasted 147 minutes. Traffic originated from 47 autonomous systems in 54 countries, predominantly residential proxy networks.

Vector WebSocket connection flood
Peak 790.7 million requests per second
Duration 147 min
Time to mitigation 0.792 s
Attack traffic reaching origin 0.051%
Legitimate traffic challenged 0.32%

Timeline

The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 508 within 37 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.
  • Lower challenge thresholds on authentication endpoints during high-risk events.
  • Add a dedicated rate limit for the targeted route.

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