The subscribe-to-PewDiePie hacking campaign continues unabated -- although it might have a positive side benefit this time around. TheHackerGiraffe (who perpetrated the earlier printer hack) has compromised thousands of Chromecast dongles, Google Home speakers and smart TVs to make them play a message that spreads both a security warning and PewDiePie propaganda. His script looks for compatible devices exposed to the internet through poorly configured routers, renames those devices to draw attention to them, and attempts to play a YouTube video warning victims to mend their ways. They're pointed to a web link (broken as of this writing) that offers help.
As Google mentioned to CNET, this isn't really a flaw with the hardware or is casting functionality. It's a bad idea to expose many devices directly to the internet, particularly if they're meant solely for in-home purposes or deal with sensitive information. You can fix this simply by configuring your router to avoid leaving devices unnecessarily exposed (in this case, ports 8008 and 8443), and turn off features like Universal Plug and Play unless you need them.
In theory, this might alert people to basic missteps while plugging PewDiePie on the side. TheHackerGiraffe stressed that it's a relatively benign effort that doesn't reset devices or otherwise do serious damage. However, it's still something of a hassle -- especially for people who aren't technically knowledgeable enough to fix the issue themselves.