'Skype was very happy to work with us on this issue. They phoned me shortly after receiving our security report and kept me up to date with their progress,' he says.

'During the patch development they called me to discuss further details, and sent me a pre-release install to verify that they had fixed the problem.'

Moore was a little surprised to find the bug in Skype because it has already undergone independent security reviews, and also because of the large numbers of users.