Hosting and distributing copyrighted software without permission is illegal.
See? Here's the deal. It's not illegal to own, it's illegal to distribute. That's all copyrights ever are, the right to distribute commercially. When you buy something, you don't buy the right to own, you buy the right to obtain a copy from a licensed vendor.
Ergo, it's not illegal to OWN, it's illegal to GIVE.
Example: I download the ROM of, say, Chrono Cross. I have obtained a copy from a source that violates the copyright law, but that illegality doesn't extend to me, the one that obtained it.
No, there's no legal standing with the word "abandonware". Technically "abandonware" is software that is not maintained any longer. Trick is with "abandonware" no one holds the right to distribute any longer. That doesn't mean you can just get it from any source.
Reverse Engineering gets tricky too. If you reverse something with the intention of using that code in another piece of software, that's illegal. If you reverse it to change the way it behaves, that's situationally illegal. No CD patches made by reversing aren't technically illegal, but they can be used to pirate. Mine doesn't because I did it myself and I own the game and don't like changing discs a lot (NO! Do NOT ask me how to do it or request that I share ANYTHING related to it with you!!!). No one has a copyright on the contents of my computer or its hard drive so I can change any byte I please, thank you very much. If FF7.exe was in the way, well....too bad for it.
