-----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN W97M.Melissa Word Macro Virus March 31, 1999 21:00 GMT Number J-037a _____________________________________________________________________________ PROBLEM: A new Word 97 macro virus named W97M.Melissa has been detected at multiple DOE sites and is known to be spreading widely. In addition to infecting your copy of Microsoft Word, the virus uses Microsoft Outlook 98 or Outlook 2000 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 98 or Outlook 2000. Word 98 on the Macintosh can be infected with this virus and will infect other documents but will not automatically send the infected documents to other users. Systems with Word and Outlook Express, Outlook 97, or other mail readers cannot automatically send the virus infected document via e-mail but Word on these systems will be infected and will infect other Word documents. 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 lost productivity 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 [Original bulletin 3/27/99] [Revision a 3/31/99] The W97M.Melissa Word macro virus has been seen within the DOE complex. This macro virus uses two methods of infection. First, it infects the Word 97 (or 2000) program (normal.dot template) and all subsequent documents edited with Word. Second, it uses the Outlook 98 (or 2000) e-mail program to mail copies of the infected document to the first 50 people in each of your Outlook address books. If Outlook 98 or Outlook 2000 is not installed, the second method of infection does not work but the first method still does. The 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, disables the Macro toolbar, and then disables the following Word 97 options (different options in Word 2000): 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 where 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 first Outlook address book, attaches the infected document and sends the message. It performs this process again for each of the address books you have defined in Outlook. After sending itself to the people in your address books, the virus 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, it has a small payload. 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. Note: we have been informed that the word Kwyjibo and the text inserted into the document are from a Bart Simpson episode where Bart wins a Scrabble game with the word Kwyjibo. Detecting The Virus =================== Most 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 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 Word from any macro virus 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. The next step is to insure that Word has been patched with the Word 97 Template vulnerability patch. The patch is available as a download from the Microsoft web site: (http://www.microsoft.com/security/bulletins/ms99-002.asp). The third step is to password protect the normal.dot global template file. The fourth step is to set the following options in the Word program. Most important is the Macro virus protection check box that causes Word to display a dialog box whenever you open a document that contains macros, giving you the option to enable or disable them. Confirm conversions at open. Macro virus protection. Prompt to save Normal template. The last step is to NEVER enable Macros in a document unless you know where they came from and know what they do. Password Protecting The Normal.dot gloal template 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 Project 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. You should never enable macros in a document unless you know where they came from and what they do. 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 with the macros diaabled, 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. An alternate protection scheme is to place the following macro on your normal.dot template in a module named AutoExec Sub Main() ' ' AutoExec.Main Macro ' Macro created 03/30/99 by William J. Orvis ' Options.VirusProtection = True Options.ConfirmConversions = True Options.SaveNormalPrompt = True MsgBox "Security Options Set" End Sub This simple macro sets the three options and displays a dialog box that says "Security Options Set" whenever you start Word. If you or a virus has disabled virus protections in Word, this macro will automatically reset them. To install this macro, perform these steps: 1. Copy the macro above from the Sub to the End Sub statements onto the clipboard. 2. Start Word 3. Choose the Tools, Macro, Visual Basic Editor command. 4. In the Project window, double click on the Normal template. You will have to type your password if you have already password protected the Normal.dot template. 5. Choose the Insert Module command. 6. Select the newly created module (Module1) and in the Properties window, change the name to AutoExec. 7. Double click on the AutoExec module to open a code window and paste the macro into the window. 8. Close the Visual Basic editor and close Word. 9. Start Word and it should display a dialog box containing the text "Security Options Set". Note: It would be a good idea to change the text displayed in the dialog box to prevent a future virus from mimicking this macro. By changing the text, only you will know what is supposed to be displayed in the dialog box. The text is set in the statement starting with MsgBox. Filtering the Virus Containing Message With a Mail Server ========================================================= If a site has been infected you may need to block the virus infected mail messages with your mail servers. For systems that use sendmail, 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 is available directly from Sendmail.com (http://www.sendmail.com/blockmelissa.html) Users of the Microsoft Exchange mailserver cannot use filters of this type. However, several vendors have indicated that they have virus scanners that operate on the Exchange server that would do the job. Check with your antivirus vendor to see if they have such a product. _____________________________________________________________________________ Thanks to Scott Hutton, CERT and Nick Christenson for the sendmail filters. _____________________________________________________________________________ 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 Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@llnl.gov For emergencies and off-hour assistance, DOE, DOE contractor sites, and the NIH may contact CIAC 24-hours a day. During off hours (5PM - 8AM PST), call the CIAC voice number 925-422-8193 and leave a message, or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC duty person, and the secondary PIN number, 8550074 is for the CIAC Project Leader. Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ (or http://ciac.llnl.gov -- they're the same machine) Anonymous FTP: ftp.ciac.org (or ciac.llnl.gov -- they're the same machine) Modem access: +1 (925) 423-4753 (28.8K baud) +1 (925) 423-3331 (28.8K baud) CIAC has several self-subscribing mailing lists for electronic publications: 1. CIAC-BULLETIN for Advisories, highest priority - time critical information and Bulletins, important computer security information; 2. SPI-ANNOUNCE for official news about Security Profile Inspector (SPI) software updates, new features, distribution and availability; 3. SPI-NOTES, for discussion of problems and solutions regarding the use of SPI products. Our mailing lists are managed by a public domain software package called Majordomo, which ignores E-mail header subject lines. To subscribe (add yourself) to one of our mailing lists, send the following request as the E-mail message body, substituting ciac-bulletin, spi-announce OR spi-notes for list-name: E-mail to ciac-listproc@llnl.gov or majordomo@rumpole.llnl.gov: subscribe list-name e.g., subscribe ciac-bulletin You will receive an acknowledgment email immediately with a confirmation that you will need to mail back to the addresses above, as per the instructions in the email. This is a partial protection to make sure you are really the one who asked to be signed up for the list in question. If you include the word 'help' in the body of an email to the above address, it will also send back an information file on how to subscribe/unsubscribe, get past issues of CIAC bulletins via email, etc. PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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