The latest entry into the field is an x64 version of the ZeroAccess rootkit, a nasty piece of malware that s been circulating for some time. The malware typically is installed on users machines via drive-by downloads that aim to exploit any one of a number of known vulnerabilities, often bugs in Adobe Reader or Java. The new version of ZeroAccess is not all that different from previous iterations, in that it’s designed to remain persistent on infected machines via rootkit hooks.
Source: https://threatpost.com/zeroaccess-rootkit-latest-line-x64-malware-appear-052411/75266/