Along with a free update to OS X 10.9 Mavericks, Apple promised owners of its iWork and iLife suites free upgrades to the latest versions, as well as anyone that bought a Mac after October 1st. However, thanks to a flaw in the company's Mac App Store, even users with trial copies are being given free editions of Apple's new software. More worryingly for Apple, users downloading illegal software are being given legitimate copies in exchange.

In addition to the iLife and iWork suites, which include Pages, Numbers, and Keynote alongside popular apps like iMovie, iPhoto, and GarageBand, the issue also extends to Aperture, which was recently updated to version 3.5. Anyone with a trial or illegal copy will get all the new features, including iCloud photo sharing, SmugMug integration, and iOS 7 filter support.

9to5Mac theorizes the issue relates to boxed copies of the software not being tied into the Mac App Store system. As each copy of Aperture has a unique serial number, that suggests the App Store is unable to check if an app has been activated. It also explains why copies that have been illegally downloaded and activated with a serial number likely used thousands of times aren't being flagged up by Apple's system: the App Store appears to only check that the software exists, without verifying where it comes from or who bought it. For Apple software without a serial number, it could be that there's no way to verify its legality at all.

Apple has never been overzealous in protecting its Mac software from piracy, but with software worth up to $200 being given away through its own store, we could see that change. Although it hasn't responded to our request for comment, Apple no longer offers trial versions of the old iWork suite, so the bug's effects are somewhat restrained.