This report of F-Secure’s Mika Ståhlberg states that MicroVault USM-F fingerprint reader software shipped with that Sony USB stick installs a driver that is hiding a directory under C:\Windows.

And – reportedly the guys of FS research laboratory

also tested the latest software version available from Sony at www.sony.net/Products/Media/Microvault/ and this version also contains the same hiding functionality. [added a hyperlink]

Hmmm – time to wear my white T-shirt with text familiar to many readers – “Most people don’t even know what a rootkit is, so why should they care about it?”