The fourth version of the TDL rootkit family is the first reliable and wideley spread bootkit targeting x64 operating systerms such as Windows Vista and Windows 7. In this report, we investigate the implementation details of the malware and the ways in which it is distributed, and consider the cybercriminals' objectives. The report begins with information about the cybercrime group involved in distributing the malware. Afterwards we go deeper into the technical detials of the bootkit implementation.