Threat Description



Aliases: Chack
Category: Malware
Type: Virus
Platform: W97M


W97M/Chack is a rather simple Microsoft Word 97 macro virus.


Automatic Disinfection

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.

Technical Details


When an infected document is opened the virus gets control. It will then disable the built-in macro virus protection and modify the customizations of Word. It disables both ALT+F8 (Tools/Macros/Macro) and ALT+F11 (Tools/Macros/Visual Basic Editor) keyboard shortcuts, removes the entire Tools/Macros submenu and disables the Visual Basic toolbar.

Then it will infect the global template. After that the virus will infect every document that is opened, created, or saved. Additionally it will hook Tools/Customize and Tools/Organizer menus.

The virus replaces the Help/About dialog with a dialog that contains a picture, a checkbox and two buttons. The same dialog will be shown in every Friday when user attempts to exit Word.

The virus code contains the following text:

     Macros By WinK'S Hacker
        Picture By Casper Satan
       Lebih baik mencoba dari pada tidak tahu sama sekali ...
        Mohon ma'af bila telah mengganggu Anda.
        Microsoft memang gila ! Nambahin fasilitas pemrogramannya
        keterlaluan untuk suatu word prosesor.
        jangan harap kau datang lagi padaku


W97M/Chack.C is similar to W97M/Chack.A. The only difference is that it does not hook "Tools/Macros/Macro" menu.


This variant is almost identical with W97M/Chack.A. It will not hook the "File/Save" menu selection, and the last line of the text in the virus code is missing.


W97M/Chack.AI is a slightly modified variant that does not hook "File/Save" or "Tools/Macros/Macro".

Description Created: Analysis: Sami Rautiainen, F-Secure


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