Computerworld posted a news story that new versions of the malware dubbed Alureon, TLD3 and Tidserv are designed to infect PCs running 64-bit versions of the OS

A new version of the malware that crippled Windows PCs last February sidesteps safeguards designed to block rootkits from hijacking machines running 64-bit editions of Windows, researchers said Thursday.

"A new era has officially dawned: the era of x64 rootkits," said Prevx researcher Marco Giuliani in a post to the security vendor's blog yesterday.

  Rootkit with Blue Screen history now targets 64-bit Windows