The logical extension is that if a virus writer applies copyright to his code (and writes it in the US) then provided he is not stealing or doing something positively illegal then no one should have any form of redress ???
Technically, they are covered by copyright automatically in the US even if they don't register or provide a copyright notice of any sort. As soon as it is offered to the public they are automatically covered until 70 years after their death.
Under current law, works are covered whether or not a copyright notice is attached and whether or not the work is registered.
EULA is a double edged sword. In some cases you are damned if you do and damned if you don't violate it.
I have been heavily involved rather recently with an issue pertaining to reverse engineering someone else's abandoned software in an effort to save a huge online chat community with millions of users from extinction.
They relied upon said software in order to build & run this community. Some have suggested reversing the software and modding it to keep it working. We decided against this approach and would rather create our own software as a replacement, even though it would be much easier to modify the original .exe. Unfortunately, most of the research into the protocols used by said software was done by those that have reversed parts of it. This is a sticky situation for the developers on the new client/server and we have had to toss out any valuable information gained by the work of reversers.
Our temporary solution is to replace/modify a file on the user's pc that isn't covered by any type of copyright in order to keep the original, unmodified software working...the system's hosts file. I was even the one that had to do the research to find out if it was legal to remove Microsoft's copyright notice from a Windows hosts file, for the creation of the first hosts patch installer. (it is if you are replacing the original file with a *nix hosts file, which is the same file without the copyright notice)
We are very serious about not violating the EULA in this case, as we will most likely end up getting sued by the RIAA any way for keeping a chat community, similar to what is found on IRC, alive. All we want is the ability to gather and express our rights to free speech in the manner in which we have become accustomed to doing so, which unfortunately is with a proprietary protocol. If we violate some EULA in the process, we will surely lose and end up being sued by more than one party, namely the original developers of the software and the RIAA, and all our work will have been in vain. (it's a P2P application)
What makes things even harder is the fact that the original developer wasn't very good with issuing patches to correct flaws and exploits that were discovered, back before he abandoned the whole thing.
We have had to create our own patches all along to protect ourselves and our chat community and those that don't even run or have ever even heard of the software. And some of them were rather nasty flaws that could be easily exploited to take over the pc's of millions users in one shot and run any code you choose.
Patching the flaws ourselves could be considered a breech of the EULA, if you really stop & think about it...but think of what could have happened if we didn't. We could have ended up with a few million zombie pc's attacking everyone and spreading malware, spam, etc.