Software giant Microsoft has been caught updating files on both Windows XP and Windows Vista without displaying the usual notification or permission dialog box - even if the user had previously disabled automatic updates. Microsoft, however, calls it built-in behavior and no cause for alarm.

Scott Dunn of "Windows Secrets", reports nine files in XP and Vista have been altered by Windows Update in what he calls a stealth move by Microsoft. The updates are upgrades to the Windows Update service itself, and are not harmful to the system. However, the tactics used by Microsoft to perform them are comparable to those used by spyware companies, thus raising some concerns among the privacy minded.

So what is happening here? Windows Update program manager Nate Clinton explains in a blog post:

To ensure on-going service reliability and operation, we must also update and enhance the Windows Update service itself, including its client side software. These upgrades are important if we are to maintain the quality of the service. [...]The point of this explanation is not to suggest that we were as transparent as we could have been; to the contrary, people have told us that we should have been clearer on how Windows Update behaves when it updates itself.
This is not the first time Microsoft has pushed updates out to users who prefer to test and install their updates manually. Back in October it was discovered that the anti-piracy program Windows Genuine Advantage was being downloaded and installed without asking users for their consent.