TLD4 is one of the most advanced Windows malware agents circulating.  It is highly stealth and hides in the master boot record of the Windows O/S.  Trend Micro shares developments related to a new version:

TDL4 Worm Component Employs Bitcoin Mining
http://blog.trendmicro.com/the-worm-tdl4-and-botcoin-miners/

QUOTE: TDL4 is a well known variant of the TDSS malware family known for evading detection by antivirus products by infecting affected systems’ boot sector. We’ve been monitoring developments related to TDSS, and earlier this year we saw TDL4 exhibit propagation routines through a worm component that Trend Micro detects as WORM_OTORUN.ASH.