Summary

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]