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[IP] CERT Advisory CA-99.04 - Melissa Macro VIRUS

To: members of the Insulin Pumpers mail lists. We have not yet 
  detected this virus on our system, but it is only a matter of time. 

There is a rapidly spreading macro virus that affects WINDOZE systems 

The CERT advisory follows.


CERT Advisory CA-99-04-Melissa-Macro-Virus

   Original issue date: Saturday March 27 1999
   Last Revised: Saturday March 27, 1999

Systems Affected

     * Machines with Microsoft Word 97 or Word 2000
     * Any mail handling system could experience performance problems
       a denial of service as a result of the propagation of this
       macro virus.


   At approximately 2:00 PM GMT-5 on Friday March 26 1999 we began
   receiving reports of a Microsoft Word 97 and Word 2000 macro virus
   which is propagating via email attachments. The number and variety
   of reports we have received indicate that this is a widespread
   attack affecting a variety of sites.

   Our analysis of this macro virus indicates that human action (in
   the form of a user opening an infected Word document) is required
   for this virus to propagate. It is possible that under some mailer
   configurations, a user might automatically open an infected
   document received in the form of an email attachment. This macro
   virus is not known to exploit any new vulnerabilities. While the
   primary transport mechanism of this virus is via email, any way of
   transferring files can also propagate the virus.

   Anti-virus software vendors have called this macro virus the
   Melissa macro or W97M_Melissa virus.

I. Description

   The Melissa macro virus propagates in the form of an email message
   containing an infected Word document as an attachment. The
   transport message has most frequently been reported to contain the
   following Subject header

      Subject: Important Message From <name>

   Where <name> is the full name of the user sending the message.

   The body of the message is a multipart MIME message containing two
   sections. The first section of the message (Content-Type:
   text/plain) contains the following text.

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

   The next section (Content-Type: application/msword) was initially
   reported to be a document called "list.doc". This document contains
   references to pornographic web sites. As this macro virus spreads
   we are likely to see documents with other names. In fact, under
   certain conditions the virus may generate attachments with
   documents created by the victim.

   When a user opens an infected .doc file with Microsoft Word97 or
   Word2000, the macro virus is immediately executed if macros are

   Upon execution, the virus first lowers the macro security settings
   to permit all macros to run when documents are opened in the
   future. Therefore, the user will not be notified when the virus is
   executed in the future.

   The macro then checks to see if the registry key


   has a value of "... by Kwyjibo". If that registry key does not
   exist or does not have a value of "... by Kwyjibo", the virus
   proceeds to propagate itself by sending an email message in the
   format described above to the first 50 entries in every MAPI
   address book readable by the user executing the macro. Keep in mind
   that if any of these email addresses are mailing lists, the message
   will be delivered to everyone on the mailing lists. In order to
   successfully propagate, the affected machine must have Microsoft
   Outlook installed; however, Outlook does not need to be the mailer
   used to read the message.

   Next, the macro virus sets the value of the registry key to "... by
   Kwyjibo". Setting this registry key causes the virus to only
   propagate once per session. If the registry key does not persist
   through sessions, the virus will propagate as described above once
   per every session when a user opens an infected document. If the
   registry key persists through sessions, the virus will no longer
   attempt to propagate even if the affected user opens an infected

   The macro then infects the Normal.dot template file. By default,
   all Word documents utilize the Normal.dot template; thus, any newly
   created Word document will be infected. Because unpatched versions
   of Word97 may trust macros in templates the virus may execute
   without warning. For more information please see:


   Finally, if the minute of the hour matches the day of the month at
   this point, the macro inserts into the current document the message
   "Twenty-two points, plus triple-word-score, plus fifty points for
   using all my letters. Game's over. I'm outta here."

   Note that if you open an infected document with macros disabled and
   look at the list of macros in this document, neither Word97 nor
   Word2000 list the macro. The code is actually VBA (Visual Basic for
   Applications) code associated with the "document.open" method. You
   can see the code by going into the Visual Basic editor.

   If you receive one of these messages, keep in mind that the message
   came from someone who is affected by this virus and they are not
   necessarily targeting you. We encourage you to contact any users
   from which you have received such a message. Also, we are
   interested in understanding the scope of this activity; therefore,
   we would appreciate if you would report any instance of this
   activity to us according to our Incident Reporting Guidelines
   document available at:


II. Impact

     * Users who open an infected document in Word97 or Word2000 with
       macros enabled will infect the Normal.dot template causing any
       documents referencing this template to be infected with this
       macro virus. If the infected document is opened by another
       user, the document, including the macro virus, will propagate.
       Note that this could cause the user's document to be propagated
       instead of the original document, and thereby leak sensitive

     * Indirectly, this virus could cause a denial of service on mail
       servers. Many large sites have reported performance problems
       with their mail servers as a result of the propagation of this

III. Solutions

     * Block messages with the signature of this virus at your mail

       With Sendmail

       Nick Christenson of sendmail.com provided information about
       configuring sendmail to filter out messages that may contain
       the Melissa virus. This information is available from the
       follow URL:
       l-m elissa-filter.txt

     * Utilize virus scanners

       Most virus scanning tools will detect and clean macro viruses.
       In order to detect and clean current viruses you must keep your
       scanning tools up to date with the latest definition files.

          + McAfee / Network Associates



          + Symantec


          + Trend Micro


     * Encourage users at your site to disable macros in Microsoft

       Notify all of your users of the problem and encourage them to
       disable macros in Word. You may also wish to encourage users to
       disable macros in any product that contains a macro language as
       this sort of problem is not limited to Microsoft Word.

       In Word97 you can disable automatic macro execution (click
       Tools/Options/General then turn on the 'Macro virus protection'
       checkbox). In Word2000 macro execution is controlled by a
       security level variable similar to Internet Explorer (click on
       Tools/Macro/Security and choose High, Medium, or Low). In that
       case, 'High' silently ignores the VBA code, Medium prompts in
       the way Word97 does to let you enable or disable the VBA code,
       and 'Low' just runs it.

       Word2000 supports Authenticode on the VB code. In the 'High'
       setting you can specify sites that you trust and code from
       those sites will run.

     * General protection from Word Macro Viruses

       For information about macro viruses in general, we encourage
       you to review the document "Free Macro AntiVirus Techniques" by
       Chengi Jimmy Kuo which is available at.



   We would like to thank Jimmy Kuo of Network Associates, Eric Allman
   and Nick Christenson of sendmail.com, Dan Schrader of Trend Micro,
   and Jason Garms and Karan Khanna of Microsoft for providing
   information used in this advisory.

   Additionally we would like to thank the many sites who reported
   this activity.

   This document is available from:

CERT/CC Contact Information

   Email: email @ redacted
          Phone: +1 412-268-7090 (24-hour hotline)
          Fax: +1 412-268-6989
          Postal address:
          CERT Coordination Center
          Software Engineering Institute
          Carnegie Mellon University
          Pittsburgh PA 15213-3890

   CERT personnel answer the hotline 08:00-20:00 EST(GMT-5) /
   EDT(GMT-4) Monday through Friday; they are on call for emergencies
   during other hours, on U.S. holidays, and on weekends.

Using encryption

   We strongly urge you to encrypt sensitive information sent by
   email. Our public PGP key is available from
   http://www.cert.org/CERT_PGP.key. If you prefer to use DES, please
   call the CERT hotline for more information.

Getting security information

   CERT publications and other security information are available from
   our web site http://www.cert.org/.

   To be added to our mailing list for advisories and bulletins, send
   email to email @ redacted and include SUBSCRIBE
   your-email-address in the subject of your message.

   Copyright 1999 Carnegie Mellon University.
   Conditions for use, disclaimers, and sponsorship information can be
   found in http://www.cert.org/legal_stuff.html.

   * "CERT" and "CERT Coordination Center" are registered in the U.S.
   Patent and Trademark Office

   Any material furnished by Carnegie Mellon University and the
   Software Engineering Institute is furnished on an "as is" basis.
   Carnegie Mellon University makes no warranties of any kind, either
   expressed or implied as to any matter including, but not limited
   to, warranty of fitness for a particular purpose or
   merchantability, exclusivity or results obtained from use of the
   material. Carnegie Mellon University does not make any warranty of
   any kind with respect to freedom from patent, trademark, or
   copyright infringement.

Revision History

Version: 2.6.2

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