Microsoft admits to a 1% false positive WGA check ratio

Microsoft recently published updated figures about the Windows Genuine Advantage protection that it implemented into the Microsoft Windows operating system. WGA has been designed to block unauthenticated versions of Windows from performing some operations, for instance the download of some software programs from the Microsoft homepage.

Software like the new Internet Explorer 7 or Windows Media Player can only be downloaded after a successful WGA check. The download and installation will be denied if a check fails, and while there are ways around that, for instance by downloading the programs from third party sites, it is seen as a nuisance by users, especially those whose systems are wrongfully identified as not genuine.

It was always known that there would be false positives and the new figures that Microsoft released give us a clearer picture on the scale of the false positive rate. About 114 million systems failed the WGA check since the introduction of those checks and Microsoft admits that this means that about 1% of all checks made are false positives meaning that legit versions of Windows were wrongfully identified as non genuine.

While under 1% does not seem that much it it does look like a lot in absolute figures: 1% of 114 million checks means that 1.14 million legit systems failed the check although this should not have happened. I can't figure out how the source comes to the conclusion that the absolute number would be 5 million false positives because you clearly have to use the failed checks for the figure and not the total amount of checks which is 500 million.

It is nevertheless a huge number and Microsoft should do anything it can to reduce it by optimizing the script that performs the checks.

Update: Microsoft changed the way WGA works in newer versions of Windows. The system is less restrictive now and while there is certainly still the chance that false positives occur, it is not really something that the majority of Windows users seem to be concerned with these days.