I was pretty concerned when I saw this yesterday, and went about doing a few things to block it, which seem to have worked so far, without limiting some of the features I want to enjoy on our system.
The first thing I did was add a rule to my Adguard custom filter to block all outgoing requests to *.sslauth.sonos.com as they seemed to relate to login activities. I don’t know if this had any effect or not, but it didn’t break anything, so I left it in place.
Then I started looking at the traffic on my devices while browsing play.sonos.com on another device at the same time. I noticed three separate IP addresses that each of my devices were talking too, and looked them up. I couldn’t tell much about them (all seemed to be AWS), but I decided to have a go at blocking outbound traffic from my devices to the ranges that the IP addresses sat in. These were:
* 35.168.0.0-35.175.255.255
* 54.196.0.0-54.197.255.255
* 54.208.0.0-54.209.255.255
I did the blocking by adding firewall rules on my router, and as I added the ranges one at a time, I saw my devices become unavailable on play.sonos.com to the extent that if I log in now, a pop up appears saying “Your speakers are offline” which suits me just fine. I would imagine that there are likely several other IP ranges that are being used to make play.sonos.com function, so we might need to build up a definitive list here.
But like I said, my devices are now no longer showing, and the functionality of the devices at home is still ok (Apple Music and Sonos Radio still work as expected, although I have no intention of using the latter).
Hopefully, at a minimum, someone at Sonos decides MFA would be a stellar idea at some point soon, but ideally we would have the option to disable this web app functionality completely and maintain a local only + services desired environment. But for now at least I can sleep slightly easier with the above blocking in place…