"Someone is using a similar technique as 'mass scanning' to massively blast raw TCP data directly to printer services across the internet," Morris told Motherboard in an online chat. "Basically to every single device that has port TCP 9100 open and print a pre-written document that references /r/antiwork with some workers rights/counter capitalist messaging."
Ok but how are these receipt printers ending up with publicly routable addresses? Nearly every ISPs is gonna give you one IPv4 address and NAT everything under that. The calls would have to be coming from inside the house.