They're probably in breach of contract too, I expect there is a click-through.

In the UK they could probably be got for "hacking" (ie cracking) as they are using the computer from which they download updates without authorisation and breaching a security feature in order to do so this puts them in contravention of the Computer Misuse Act (or at least on a naive reading, mine, it does so).

I'm sure many of these people are violating copyright to get a copy of the installer, but surely that can't be the main law being broken. Avoiding the specifics of Avast that I don't know, if they can get the installer from the producer, maybe because there's a trial, there can't be a copyright violation when no unauthorized copies are made, can it? So what is the exact law being broken?