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Ex-hacker: 'It's easy to break into companies like Sony'

19 December 2014 Last updated at 02:53 GMT

The White House has described the cyber attack on Sony Pictures as a serious national security matter.

So just how easy is it to hack into a conglomerate like Sony?

The BBC's Alistair Leithead went to meet Marc Maiffret, a former hacker who is now an internet security expert.