Comment by ThiefMaster-

You probably don't need a virus or anything running in the end user's network.

If your Sonos can access the API to mark a device as recycled, so can you. So if you can predict serial numbers or just bruteforce them (depending on how complex they are) you might be able to brick every single Sonos out there...

I highly doubt they assign unique keypairs etc. to every single device...