Summary

W97M/Mmkv is a Word 97 macro virus with destructive payload.

The virus gets control when an infected document is opened, and then the virus infects the global template.

After that it infects all documents that are opened or saved.

The virus hooks "Tools/Macros/Macro" dialog and "Tools/Macros/Visual Basic Editor" rendering them unusable.

Additional Details

VARIANT:

Mmkv.A

The payload of W97M/Mmkv.A activates on any day of the year 2000. Then the virus deletes all files from both the current directory and the root of the "C:" drive. Finally the virus show a message box with a title:

MK-Words By MMK 1999
and with the text:

Welcome To Y2K

VARIANT:

Mmkv.B

W97M/Mmkv.B has two different payloads. The first activates every 3rd day of each month and then the virus shows a message box with the following title:

MK-Words By MMK 1999
and with the following text:

Y2K is coming soon...
The second payload activates any day of the year 2000 and at this time the virus drops an executable binary file "c:\end.com", and executes it. This binary file attempts to format the 9th track of the first hard drive, in effect destroying the root directory and FAT of the first partition.

Then the virus shows a message box with the same title as before but with the text:

Welcome To Y2K

VARIANT:

Mmkv.C

W97M/Mmkv.C is a slightly modified variant of the W97M/Mmkv.B. When the payload activates, this variant creates a file "c:\end.a", but it will be never executed.

[Analysis: Sami Rautiainen and Alexey Podrezov, F-Secure]