When a user installs Windows Genuine Advantage, an Internet Explorer add-on is installed labeled "Windows Genuine Advantage".
In early releases, the tool could be readily disabled with the IE Add-on Management feature.
A Windows Group Policy was added by later updates, causing this option to be unavailable by default, but still accessible if the policy were removed. As of July 2006, the latest update blocks management by other means.
The program uses either a stand-alone program to generate a key or an ActiveX control to discover whether the license key is valid; either way, an Internet connection is required.
On Windows XP, if WGA determines that a user's copy of Windows is unauthorized, but was installed from seemingly legitimate media (i.e., the CD/DVD and holographic emblem present on real copies of Windows seems genuine), then Microsoft will supply the user with a new CD/DVD. However, newer versions of Windows will still require the user to purchase a new copy. Microsoft also offers discounts to people who want to purchase a legitimate copy of Windows but do not have a valid CD. Microsoft has indicated that they will continue to deliver critical security updates through their Automatic Updates service as well as via the Microsoft Download Center, so that all systems, including those that fail to pass validation, will still continue to receive critical security updates.
The company has made installation of Windows Genuine Advantage a requirement for use of the Windows Update and Microsoft Update websites, in part to be sure that customers who use support resources of the company are aware when their software is unlicensed. According to Microsoft themselves, it is legal to run Microsoft Windows without Windows Genuine Advantage.
However, since non-critical Windows updates are not presented by Automatic Updates, installation of WGA is required for installation of such non-critical updates, which are only available through Windows Update or the Microsoft Download Center.
WGA Notifications
On April 25, 2006, Microsoft began distributing Windows Genuine Advantage Notifications[4] as "critical update" KB905474 to Windows users. For Windows 7, KB971033 has the same function.[5] Back in 2006, users with copies the WGA believed to be unlicensed were exposed to alerts[6] at startup, login, and during use of the Windows OS, stating that they do not have a genuine copy of Windows. Users with legitimate copies are not supposed to see the alerts (although some do anyway[7]). On May 23, 2006, Microsoft updated the program, closing some forms of circumvention, but reportedly not all.[8]
WGA Validation Library
Microsoft includes the Windows Genuine Advantage Validation Library in several products, such as Windows validation tool or Windows Media Player 11, to check the validation about all Windows software. As of version 7, Internet Explorer no longer requires the user to pass a Windows Genuine Advantage test in order to download or install the software.
The WGA Validation Library is also included in the Microsoft Security Essentials 2.0 and validate the Windows installation whether it is legitimate or not. The program will stop working after 30 days once it failed the validation process.
The information is then used in the WGA Library to check for overuse of license keys.