Re/code is reporting that Sony is using Amazon Web Services to rent cloud computer power, and aim traffic at sites offering the company's files for download.
Sony's attack is actually similar to a tactic used by cyber-criminals. When hackers want to take down a website, they point huge amounts of internet traffic at it. That's called a "distributed denial of service" attack. Sony is essentially doing the same thing to fight back against hackers.
Re/code says that Sony is using Amazon's online cloud computing supplier to create a flood of fake "seed" sources for the stolen documents, which are available as torrent files (a peer to peer file sharing service that lets dozens of people share bits of files simultaneously). Anyone requesting a torrent copy of the seed file is likely to get a fake seed - and thus won't get the documents.
Sony realises that it can't stop everyone downloading the documents (they're all over the internet). But what it can do is disrupt the networks offering them, making them more difficult to obtain.
The move is interesting in part because it shows that Sony isn't just a hapless victim of hackers. It has some tech tools of its own with which is can fight a rearguard action.
The tactic of frustrating internet users into quitting their illicit activity is one that Hollywood has been doing for years. Major movie studios upload fake copies of mainstream movies to file-sharing sites. Users only realise the files are fake after spending hours downloading them, which movie studios hope will deter them from illegal file-sharing in the future.