Opening a WebSocket channel and keeping it alive
https://www.bleepingcomputer.com/news/security/new-purplefox-botnet-variant-uses-websockets-for-c2-communication/
The PurpleFox botnet has refreshed its arsenal with new vulnerability exploits and dropped payloads, now also leveraging WebSockets for C2 bidirectional communication.
Although it's mainly based in China, the PurpleFox botnet still has a global presence through hundreds of compromised servers.