Virus Profile: W97M/Class.f

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Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 9/9/1998
Date Added: 6/29/2000
Origin: Unknown
Length: N/A
Type: Virus
Subtype: Macro
DAT Required: 4002
Removal Instructions


This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.

Indication of Infection

Message box display on July 28 when opening infected documents. Macro warning when opening infected documents on non-infected system and macro warning is enabled before hand.

Methods of Infection

This virus hooks the Word event handler of opening documents in order to run its code. Once the global template NORMAL.DOT is infected, any document used on the system will become infected.


Class.f, Macro.Word97.Bug, W97M.Class.F, WM97/Woobie, Woobie

Virus Characteristics

This is a class module macro virus for Word97 documents and templates. This virus does not infect as intended on Word2000 environments due to errors in the virus code. This virus does not have a destructive payload although it does have a date activated payload of displaying an image box. This virus will lower macro warning settings.

This virus consists of one class module and one form module. The class module name is typically "Thisdocument" while the form module is named after the user initials of the infected user.

If an document is opened on an infected system and the date is July 28th, a message box will be displayed. See related images for this message box.

All Users :
Script,Batch,Macro and non memory-resident:
Use current engine and DAT files for detection and removal.

PE,Trojan,Internet Worm and memory resident :
Use specified engine and DAT files for detection. To remove, boot to MS-DOS mode or use a boot diskette and use the command line scanner:


Additional Windows ME/XP removal considerations

Users should not trust file icons, particularly when receiving files from others via P2P clients, IRC, email or other mediums where users can share files.

AVERT Recommended Updates :

* Office2000 Updates

* Malformed Word Document Could Enable Macro to Run Automatically (Information/Patch )

* scriptlet.typelib/Eyedog vulnerability patch

* Outlook as an email attachment security update

* Exchange 5.5 post SP3 Information Store Patch 5.5.2652.42 - this patch corrects detection issues with GroupShield

For a list of attachments blocked by the Outlook patch and a general FAQ, visit this link .
Additionally, Network Administrators can configure this update using an available tool - visit this link for more information .

It is very common for macro viruses to disable options within Office applications for example in Word, the macro protection warning commonly is disabled. After cleaning macro viruses, ensure that your previously set options are again enabled.


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