If you are a fan of Little Snitch, or would like to better manage who your Mac is talking to, check out LuLu.  LuLu is a free open-source Mac firewall that blocks unknown/unauthorized outgoing connections, written by Patrick Wardle of Objective-See.  It is highly configurable, enterprise friendly, and can generically detect malware. LuLu requires macOS 10.12 or later.