From ciac@rumpole.llnl.gov Mon Mar 29 00:11:46 1999
From: CIAC Mail User <ciac@rumpole.llnl.gov>
To: ciac-bulletin@rumpole.llnl.gov
Date: Sat, 27 Mar 1999 12:45:38 -0800 (PST)
Subject: CIAC Bulletin J-037: W97M.Melissa Word Macro Virus

[  For Public Release  ]
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             __________________________________________________________

                       The U.S. Department of Energy
                    Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___
             __________________________________________________________

                             INFORMATION BULLETIN

                         W97M.Melissa Word Macro Virus

March 27, 1999 17:00 GMT                                        Number J-037
_____________________________________________________________________________
PROBLEM:       A new Word 97 macro virus named W97M.Malissa has been detected 
               at multiple DOE sites and is known to be spreading widely. The 
               virus uses Microsoft Outlook to e-mail the infected document 
               to the first 50 people from each of your Outlook address books.
PLATFORM:      Windows 95 or Windows NT running Microsoft Word 97 (version 8) 
               or Word 2000 (version 9) and Microsoft Outlook. Word 98 on the 
               Macintosh is probably not vulnerable because the virus uses
               the Windows registry, but that has not been verified yet.  
               Outlook Express and other mail readers are not vulnerable. 
DAMAGE:        It overwrites the first macro in open documents and in the 
               normal.dot template with the macro virus code. It turns off 
               macro detection in Word. It sends copies of the infected 
               document to up to 50 people from each of your Outlook address 
               books. 
SOLUTION:      Use an updated antivirus product. Some vendors have a solution 
               available but in many cases you must go to the vendors web
               site to get it. Do not depend on the automatic or live update 
               feature of an antivirus package to get the detector for this 
               virus. Additional precautions are to password protect the 
               normal.dot file, turn on macro virus detection in Word, and DO 
               NOT OPEN attachments to mail messages with the subject 
               "Important Message From " and the contents "Here is that 
               document you asked for ... don't show anyone else ;-)" without 
               checking with the sender. Alert your computer security
               officers  if you receive such messages.
_____________________________________________________________________________
VULNERABILITY  Risk of infection is high. This virus is spreading widely 
ASSESSMENT:    within and without of the DOE complex. The risk of damage to 
               your system is low because most users do not have macros in  
               files and would be alerted by Word's macro detector. The risk  
               of lostproductivity and lost mail messages is high as mail  
               servers may have to be shut down and purged of infected mail 
               messages. 
_____________________________________________________________________________
   CIAC has critical information about the W97M.Melissa Word Macro Virus

The W97M.Malissa Word macro virus has been seen within the DOE complex. This 
macro virus attaches to Word objects in Word 97 and Word 2000. Because of
this method of infection, this virus will not infect older versions of  
Microsoft Word. When an infected document is opened, the virus checks to  
see if Word 97 or Word 2000 is installed and then disables the Macro
toolbar.   
It then disables the following Word options:

  Confirm conversions at open.
  Macro virus protection.
  Prompt to save Normal template.

Disabling these options makes it difficult to detect the virus in action. The 
virus next checks the value of the private registry string:

  HKEY_CURRENT_USER\Software\Microsoft\Office\Melissa? 

If that string is not equal to "... by Kwyjibo" the virus sends copies of the 
infected document to the first 50 people in each of your Outlook address 
books and then sets the registry key so it does not do this again. It sends 
copies of the infected document to others by opening a connection to Microsoft
Outlook and creating an e-mail message with the subject:

  Important Message From <username>

where <username> is replaced with the current Word user's name (Tools, Options
command, User Information tab). The body of the message contains the following
text: 

  Here is that document you asked for ... don't show anyone else ;-)

The virus then inserts the first 50 users from your Outlook address book, 
attaches the infected document and sends the message. It does this for however
many address books you have defined in Outlook.

After sending itself to the people in your address books, the virus then
checks to see if it is running on a document or the Normal.dot template. If  
it is running on a document, it infects the Normal.dot template with a
Document_Close macro that runs whenever a document is closed. If it is  
running on the Normal.dot template, it infects the active document with a 
Document_Open macro that runs whenever a document is opened. After the 
Normal.dot template is infected, the virus infects every document you work 
on as soon as you close them. If you share these documents with anyone, you 
will spread the virus.

Finally, if the minute of the hour equals the day of the month, the virus 
inserts the following message at the current location in the active document.

  Twenty-two points, plus triple-word-score, plus fifty points for using 
  all my letters.  Game's over.  I'm outta here.

Detecting The Virus
===================

Several antivirus vendors have a detection and cleaning capability for this 
virus; however, you must go to the vendors web site to get the scanner 
updates. Scanners with automatic or live update features do not yet get the  
update required to find and clean this virus. While we expect the detection  
strings to be in the automatic updates in the near future, for the next
week or two you should get the scanner directly from your vendor's web site.
We have verified that the Norton Antivirus updater obtained from the 
Symantec web site (http://www.symantec.com/techsupp/custom/mailissa.html)
does detect the virus, the current live update does not. We have reliable 
information that McAfee (http://vil.mcafee.com/vil/vm10120.asp), and 
Trend Micro (http://housecall.antivirus.com/smex_housecall/technotes.html)  
also have detection capabilities.

If you receive an e-mail with the following subject and body, DO NOT OPEN the 
attachment. 

Subject: 
  Important Message From <username>
Body: 
  Here is that document you asked for ... don't show anyone else ;-)

Make sure the sender is someone you know and then ask them if they really 
sent you the attachment before opening it. If they did not send it, do not 
open the attachment and contact your computer security manager. The most 
common name for the attached file is list1.doc but that name can change.

If the following text appears in a document without your putting it there, 
your normal.dot template is infected and your Word program is infecting all 
documents when you close them.

  Twenty-two points, plus triple-word-score, plus fifty points for using 
  all my letters.  Game's over.  I'm outta here.


Another option to see if a system has been infected is to use Regedit and 
search for the following registry key:

HKEY_CURRENT_USER\Software\Microsoft\Office\Melissa?

If that key exists and has the value "... by Kwyjibo" the system has been 
infected at some time. Note that the infection may have been removed without 
deleting the key. This key can be deleted, but does no damage if left alone.

Protecting A System
===================

The first step in protecting a system is to have a current antivirus package 
running on your system. Be sure to update it at least once a month. Many of
the newer antivirus scanners have the capability to automatically update
themselves every couple of weeks. 

To protect Word from this and other Word macro viruses, first insure that Word
has been patched with the Word 97 Template vulnerability patch 
(http://www.microsoft.com/security/bulletins/ms99-002.asp); second, the 
normal.dot template file should be password protected; and third, the
following Word 97 options should be enabled. 

  Confirm conversions at open.
  Macro virus protection.
  Prompt to save Normal template.

Password Protecting The Normal.dot File
- - - - - ---------------------------------------

To password protect the Normal.dot file in Word 97, perform these steps:

1. Start Word.
2. Choose the Tools, Macro, Visual Basic Editor command.
3. In the Project window of the Visual Basic Editor, click on Normal.
4. Choose the Tools, Normal Properties command, Protection tab.
5. Check the Lock Projebt for Viewing check box and type in a password twice. 
6. Close the dialog box, close the Visual Basic editor.
7. Quit Word.

The next time you start Word, the normal.dot template will be protected. 

WARNING: If you ever have to type in the password to make changes to the 
normal.dot file be aware that the file remains unprotected until you quit
Word and restart it. 

Turning On Macro Virus Protection and Other Options
- ---------------------------------------------------

Some simple macro virus protection is built into Word 97. It does not detect 
specific macro viruses but only informs you if macros exist on a document you
are trying to open. Macros detected by Macro Virus Protection are not 
necessarily a virus. However, if you are alerted to a macro attached to a 
document you should be extremely wary because most people do not have macros
attached to their documents. 

Other options to set are: 

  Confirm conversions at open. This makes Word display a dialog box if 
    it is converting a document from one format to another.

  Prompt to save Normal template. This makes Word display a dialog box 
    asking you to confirm changes to the Normal.dot template. Most 
    macro viruses hide in Normal.dot so this lets you know that there 
    has been a change that you may want to prevent. Changes also occur 
    when you change the default font or one of the built-in styles.


To turn on macro virus protection and these other options, perform these
steps:

1. Start Word.
2. Choose the Tools, Options command, General tab.
3. Check the Macro Virus Protection check box.
4. Check the Confirm conversions at open check box.
5. Choose the Save tab.
6. Check the Prompt to save Normal template check box.
4. Close the dialog box.

Whenever you open a document that contains macros, the macro virus protection 
opens a dialog box telling you that there are macros in the document and
giving you the option to: Open the document with the macros enabled, open 
the document without the macros, or cancel the open operation. You should  
only open a document with macros enabled if you are expecting there to be 
macros on that document and you know what they are supposed to do.

Detecting the Virus With a Mail Server
======================================

If a site has been infected you may need to block the virus infected mail 
messages with your mail servers. The following filter was written by Scott 
Hutton (Lead Security Engineer, Information Technology Security Office) of 
Indiana University. As Scott mentions, this filter blocks all messages with
the text "Important Message From" in the subject line, which may block 
messages that do not contain the virus. Use this filter at your own 
discretion. 

===== start included text ======
We blocked this on our mail relays through the following additions to
the sendmail.cf:

  HSubject: $>CheckSubject
  SCheckSubject
  RImportant Message From $+  $#error $: 553 Subject Error
  R$*        $@ OK

Don't forget that there are tabs before $#error and $@ OK.  This will
block any message where the subject begins with "Important Message
>From ...", which may be too rash of an action at your site.

===== end included text ======

Another filter was obtained by the CERT team from Nick Christenson of 
sendmail.com

ftp://ftp.cert.org/pub/cert_advisories/Patches/CA-99-04-sendmail-melissa-
filter.txt
_____________________________________________________________________________
Thanks to Scott Hutton for the preliminary analysis and for a sendmail 
filter. Thanks to CERT and Nick Christenson of sendmail.com for another 
sendmail filter.
_____________________________________________________________________________

CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
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