Virus Profile: W97M/Concon

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Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 4/26/2000
Date Added: 5/1/2000
Origin: Unknown
Length: N/A
Type: Virus
Subtype: Macro
DAT Required: 4077
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

This virus contains a date activated payload. When closing infected documents on the 31st of the month, the registry is modified to run execute a system crashing instruction:

Run = c:\con\con

This instruction will run at next Windows startup and may cause a sytem crash. Microsoft has published an update and description for this exploit at this link.

In order for the virus to trick a user into restarting Windows, the following "critical" message box is displayed after modifying the registry with the above change:

Shutdown all applications and reboot

Methods of Infection

This virus writes its source code to the root of C: as "c:\boot.386". The source code is imported as a macro module into host documents by this virus. Once the global template is infected, all documents used on the system will become infected.



Related Viruses


Virus Characteristics

This is a macro virus for Word97/2000 documents and templates. This virus contains a date activated payload which is designed to crash Windows if executed.

This virus exists in a macro module named "concon". The code intercepts the Word event handler of closing documents due to a subroutine named "Autoclose".

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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