A hacker is claiming to have hacked a Mac OS X server system in under 30 minutes.

The hacker won a Swedish competition last month in which hackers were invited to break into a system. He managed to take root control of the machine - allowing him to delete files and folders and install applications - within six hours of the competition launching.

The hacker calls himself "gwerdna". He told ZDNet Australia: "It probably took about 20 or 30 minutes to get root on the box. Initially I tried looking around the box for certain mis-configurations and other obvious things but then I decided to use some unpublished exploits -- of which there are a lot for Mac OS X."

He said the hacked Mac could have been better protected, but he would still have been able to achieve the result as he used a vulnerability that hasn't yet been recognised or repaired.

He conceded that Apple's best protection against hackers comes from its relatively low market share.