OneHalf
OneHalf is a DOS-based polymorphic computer virus (hybrid boot and file infector) discovered in October 1994. It is also known as Slovak Bomber, Freelove or Explosion-II. It infects the master boot record (MBR) of the hard disk, and any files with extensions .COM, .SCR and .EXE. However, it will not infect files that have SCAN, CLEAN, FINDVIRU, GUARD, NOD, VSAFE, MSAV or CHKDSK in the name.