Cobra.A is a Word 97 virus that contains a destructive payload.
The virus infects when a document is opened, closed or saved.
When the current date is September 11 and a document is closed,
the virus inserts a small code in another module - the class
module ThisDocument. This code activates when a user exits Word
application. Than the virus show a message box with a tittle
"Cobra" and the following contents:
"You are infected with Cobra"
When FileSaveAs is used Cobra.A creates additional module
ComCity. This code activates when a new file is created. If the
date is October 11 the virus deletes all the files on "C:\"
drive.
Cobra.F is a mass-mailer and spreads via email as the Melissa
virus.
The main part of the virus code, the replicating and the
mass-mailing parts are in "BornCobra" module.
When an infected document is opened or closed the virus adds a
registry key "Cobra". It changes also the registered Windows
owner to "Cobra" and the registered organization to "DHK/BD".
After that it replicates and executes its mass-mailing part.
Using Outlook application the virus sends an email message to the
first 30 recipients from each users address book. The e-mail
message looks as follows:
From: (name of the infected user)
Subject: "Important Message From Microsoft Via " (name of
the infected user)
Body: "Important documment"
Attachment: (infected active document)
Cobra.F also disable the build-in macro virus protection and
Tools/Macro menu.
The virus creates another module named "Cobra" that contains a
destructive payload. It executes when a new file is created. If
the number of the current day and month are the same, it deletes
all directories from "C:" drive in a hidden DOS process.
This variant infects during opening, closing documents and exit
MS Word application.
The virus uses two modules: Cobra_20C in infected global template
and NewCobra (that is the same) and MoreInfect in infected documents.
The code in NewCobra (Cobra_20C) module contains the replicating code.
It first removes Tools/Macro and View/Toolbars menus. Then it
disables Alt/F8 and Alt/F11 that are the keys for Tools/Macro and
Visual Basic Editor. This code extracts the payload of the virus
that it places in MoreInfect module.
It modifies the registry to change the Windows registered owner
to "Cobra" and registered organization to "349,PB/ER/DHK-1217/BD".
In addition it creates a registry key to keep the date of the
initial infection. If the system has been infected for more then
60 days, then during creating a new Word document the virus tries
to deletes the recent file list of Excel 8.0.
On the top of its code the virus contains the following commented
text:
'Cobra Version 2.0C
[Analysis: Katrin Tocheva, F-Secure; November 2000]
