As a result of its decision to include a rootkit-based copy protection system in some of its CDs, Sony had to pay $1.5 million in civil penalties and refund users whose PCs were damaged by the software last year. However, it seems that wasn't enough to make the company turn its back on rootkits.
The folks at F-Secure have discovered that software bundled with Sony's MicroVault USB thumb drives installs a driver intended to conceal files in the host system's Windows directory. Said directory reportedly becomes invisible to the Windows API and some anti-virus software, which could potentially allow malware to exploit it in order to avoid detection.
According to F-Secure, Sony relies on the cloaking functionality to conceal data used by the thumb drives' fingerprint authentication system. (Thanks to Slashdot for the tip.)