It seems that there's been some murky goings-on with Microsoft's latest round of Windows updates.

Windows-watchers have discovered that as well as the publicised updates, Microsoft has installed a series small updates to XP and Vista user's system files without the user's knowledge or permission, and has even managed to carry out these unofficial updates even when preferences were set to manual updates only.

Windows Secrets were one of the first to discover these events and reported that Windows Update had been: "altering files on users' systems without displaying any dialog box to request permission. The only altered files that have been reported to date are 18 small executables used by WU itself. Microsoft is patching these files silently, even if auto-updates have been disabled on a particular PC".

Although the technical side of this news will most likely not be of concern to most consumers who tend to leave all updates on auto anyway, system administrators might find this problematic, but the much larger, wider concern being raised is: how ethical is it for Microsoft to sneak in unacknowledged changes?

"From the perspective of businesses, it isn't a good thing", said Andrew Jaquith, program manager for Security Research. "Silent updates are probably against corporate policy and will definitely mess up whitelisting programs if those are installed."

There's been no official comment from Microsoft yet.