whisper network

noun2

1. •
   Any informal network of people who share information or gossip.

   • There is a whisper network in Bisbee, of codes and messages telling weary crossers where they can stay, safely hidden from the border patrol. — 2001
2. •
   An informal network of women privately sharing information, typically of people alleged to be sexual harassers, abusers, or rapists.

   • The truth is whisper networks were never meant to be the end-all solution for harassment and abuse; they’re triage. We just want to stop the bleeding. — 2018