When an infected document is opened, W97M/FF.A deletes the
"Tools/Macros" menu and disables the built-in macro virus
protection first. Then the virus creates a temporary file,
"C:\FF.sys", and infects the global template.
Afterwards every opened document is infected.
the virus activates its payload on the first day of every month. It
alters the "c:\msdos.sys" file by changing the
This causes Windows 95/98 to start in command line mode after boot,
instead of graphical user interface (GUI).