This is a Microsoft Excel macro virus. Sofa spreads to Excel
spreadsheets once it has copied its virus code to the default
startup directory. It does this by creating a file called
\MSOFFICE\EXCEL\STARTUP\BOOK.XLT
Sofa contains these macros: Auto_Open, Auto_Range, Current_Open,
and Auto_Close.
Sofa activates by checking the title bar text of Excel to read
Microsofa Excel
Otherwise, the virus just spreads.
Sofa was found in the wild in USA in December 1996.
See: ExcelMacro/Laroux
[Analysis: Mikko Hypponen, F-Secure]
