The software maker said on Thursday that the update is aimed at thwarting a technique that was letting some people use pirated versions of the operating system without going through the software's built-in product activation. Microsoft has dubbed the approach "frankenbuild" because it works by combining test versions of Vista with the final code to create a hybrid version.
"Windows Vista will use the new Windows Update client to require only the 'frankenbuild' systems to go through a genuine validation check," Microsoft said on its Windows Genuine Advantage program blog. "These systems will fail that check because we have blocked the [product] keys for systems not authorised to use them."
Although Vista was only released to businesses last month ? and won't hit retail shelves until late January ? it has been making the rounds on the internet, and there have been several reported hacks to bypass its built-in security mechanisms.