It is a stealth Excel97 macro virus. It infects workbooks on their closing. While infecting the virus saves its code in sheets as "class" macros (see also "Macro.Word97.Class"). It also creates the infected MsOffice8.xls file in the Excel startup directory and disables the Macro Virus Protection by direct access to system registry.
Each time an infected document is being closed, the virus creates in the "C:WindowsSystem" folder several files with names generated using current date and time and extension ".INF"
