Zbtlink routers ship with 'Endlessdoors' backdoor that gives unauthenticated root access
VulnCheck’s analysis of 20 Zbtlink router models uncovered the ENDLESSDOORS implant – a hidden rctl binary that phones home to a Chinese C2 every 35 seconds and executes arbitrary root commands on demand. The backdoor, present in all firmware releases over two years, exposes any network using these devices to full remote control.