Marker.C is a macro virus that infects Word's global template (NORMAL.DOT file) and all the documents generated with it. By doing so, it will infect all the documents that the user opens, closes, saves, etc.
When Marker.C is run, it disables the macro antivirus protection. This means that the dialog box that prompts the user to enable or disable the macros that the document contains, is not displayed. By doing so, Marker.C prevents the user from disabling the macro used by the virus to carry out its infections.
Marker.C reaches computers in an infected Word document (a file with a DOC extension), using the typical means of virus transmission, among others, floppy disks, CD-ROMs, e-mail messages with attached files, Internet downloads, FTP, IRC channels, peer-to-peer (P2P) file sharing networks, etc.