Classification

Category :

Malware

Type :

Virus

Aliases :

Verlor

Summary

W97M/Verlor is a Word 97 macro virus.

Removal

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.

Technical Details

Variant:Verlor.A

When an infected document is closed, the virus drops two files to the Windows directory, "tempad.dll" and "tempnt.dll". These files are used to infect the active document and the global template.

As an infection marker, the virus uses the word "Overlord".

Then it creates a text file, "c:\Himem.sys". This file is used to keep names of the infected documents.

If user attempts to see the code via "Tools\Macros\Visual Basic Editor", the virus hides itself by calling a stealth function. It modifies the registered owner of Windows to "the Overlord". Then the virus alters the "win.ini" in the Windows directory in a such way, that a VBS file "overlord.b.vbs" will be executed when the system is restarted. The the virus removes itself from the global template and all active documents.

The "overlord.b.vbs" infects the global template and it uses the "c:\himem.sys" to infect all files that are listed there.

When "Tools\Macros\Macro" is accessed, the virus uses another stealh mechanism. It deletes its code from the global template and all opened documents before the "Tools\Macros\Macro" dialog is shown. Later it infects them back after the dialog is closed using different method of infection.