XM/Compat.A is a polymorphic macro virus. The virus changes its appearance so it looks different in every infected file. This is done by inserting random comments into the virus code.
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First check if your F-Secure security program is using the latest updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.
The virus consists of 11 subroutines: Auto_Open, Auto_Close, Auto_Exit, Auto_Help, Macro1, Macro2, Macro3, Macro4, Macro5, Macro6, and Macro7. They are in one module which has polymorphic name.
The virus puts the following comment in the beginning of its code:
Macro recorded (month)/(day)/(year) by (user)
The variables (month), (day), (year) and (user) are different for every environment and replication. The virus saves its code in different files and paths depending on the environment.
On Macintosh, the files are "Office 97 Compatibility" and "MS Excel Visual Basic Example", but on Windows 95 they are "Off97com.xla" and "Vba_xl.txt".
The virus builds its code as Add-In in Off97com.xla file. Compat works only in Excel 95. It does not infect Excel 97.
Compat has a payload which activates after 31 August 1998. After that date, the virus modifies the contents of random cells by changing the values slightly. This can have disasterous effects.