This virus is able to replicate under the SR-1 release of Word 97. It will turn off the macro warning feature of Word 97. This virus uses the "ThisDocument" stream, or class module, of a document or template during infection routine. It is a copy-cat of the W97M/Melissa.a virus and there is a payload to send the infected file via MS Outlook.
Another payload exists for this virus which is date activated - December 25th - to reformat the hard drive (on Windows 9x systems) and also overlay the active document with random shapes. Due to this overlay activation which is a copied technique of the W97M/Pri virus, the name is a combination of W97M/Melissa and W97M/Pri, hence W97M/Prilissa.

This virus hooks the system event of opening documents in Word97 by the subroutine "Document_Open" thereby running its code. Another system event hooked is the closing of documents due to the subroutine "Document_Close" in the global template after infection.

This virus checks for the existence of a registry key, a self-check to verify if the local system has already been infected. The key is:

"HKCU\Software\Microsoft\Office\" "CyberNET"="(C)1999 -
Indonesia by AnomOke!"

If this key is not found, the virus code uses VBA instructions to create a MS Outlook email message with the subject line "Message From " (Office97 UserName) and a message body of "This document is very Important and you've GOT to read this !!!". The first 50 listings from all available address books are selected as the recipient - the message is then sent with an attachment of the infected document. Lastly, the virus code creates the registry key.

If this key does exist, the email propagation is not repeated.

If the date is December 25th (any year), the virus runs a destructive payload to overwrite the existing C:\AUTOEXEC.BAT file with the following instructions:
"@echo off"
"@echo Vine...Vide...Vice...Moslem Power Never Ends

Indications Of Infection
Macro warning if opening infected document, increase in size to global template. Messages on screen as mentioned above. Email propagation as mentioned above.

Method Of Infection
Opening infected documents will infect global template normal.dot.

Removal Instructions
Script,Batch,Macro and non memory-resident:
Use specified 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 an emergency boot diskette and use the command line scanner such as:

SCANPM C: /CLEAN /ALL

AVERT Recommended Updates:

* scriptlet.typelib/Eyedog vulnerability patch

* Malformed E-mail MIME Header 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.