By: George Rudzinski Re: Macrovirus 1 DOCUMENT TITLE: New macro viruses target Word docume

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By: George Rudzinski Re: Macrovirus 1 DOCUMENT TITLE: New macro viruses target Word document files New macro viruses target Word document files Date: 23rd of August, 1995, updated 27th of October. Same information in Finnish / Suomenkielinen versio ˙˙˙Introduction ˙˙˙WordMacro/DMV ˙˙˙WordMacro/Concept ˙˙˙WordMacro/Nuclear ˙˙˙NEW! WordMacro/Colors ˙˙˙Protecting yourself against macro viruses Introduction Macro viruses are not a new concept - they were predicted as early as the late eighties. At that time, the first studies about the possibility of writing viruses with the macro languages of certain applications were made. However, macro viruses are not just a theory any more. Currently, there are several known macro viruses. They have all been written with WordBasic, the powerful macro language of Microsoft Word. These viruses spread through Word documents - Word's advanced template system makes it an opportune environment for viral mischief. This is problematic, because people exchange document a lot more than executables or floppy disks. Macro viruses are also very easy to create or modify. Although other word processors like WordPerfect and Ami Pro do support reading Word documents, they can not be infected by these viruses. It is not impossible to write similar viruses for these systems, however. WordMacro/DMV WordMacro/DMV is probably the first Word macro virus to have been written. It is test virus, written by a person called Joel McNamara to study the behavior of macro viruses. As such, it is no threat - it announces its presence in the system, and keeps the user informed of its actions. Mr. McNamara wrote WordMacro/DMV for over a year ago, in fall 1994 - at the same time, he published a detailed study about macro viruses. He kept his test virus under wraps until a real macro virus, WordMacro/ Concept, was recently discovered. At that time, he decided to make WordMacro/DMV known to the public. We oppose to such behaviour; although it can be argued that spreading such information will educate the public, we can also except to see new variants of the DMV virus, as well as totally new viruses inspired by the techniques used in this virus. McNamara also published a skeleton for a virus to infect Microsoft Excel spreadsheet files. F-PROT Professional 2.20 is able to the detect the WordMacro/DMV macro virus. WordMacro/Concept WordMacro/Concept - also known as Word Prank Macro or WW6Macro - is a real macro virus which has been written with the Microsoft Word v6.x macro language. It has been reported in several countries, and seems to have no trouble propagating in the wild. WordMacro/Concept consists of several Word macros. Since Word macros are carried with Word documents themselves, the virus is able to spread through document files. This is a quite ominous development - so far, people have only had to worry about infections in their program files. The situation is made worse by the fact that WordMacro/ Concept is also able to function with Microsoft Word for Windows 6.x and 7.x, Word for Macintosh 6.x, as well as in Windows 95 and Windows NT environments. It is, truly, the first functional multi- environment virus, although it can be argued that the effective operating system of this virus is Microsoft Word, not Windows or MacOS. The virus gets executed every time an infected document is opened. It tries to infect Word's global document template, NORMAL.DOT (which is also capable of holding macros). If it finds either the macro "PayLoad" or "FileSaveAs" already on the template, it assumes that the template is already infected and ceases its functioning. If the virus does not find "PayLoad" or "FileSaveAs" in NORMAL.DOT, it starts copies the viral macros to the template and displays a small dialog box on the screen. The box contains the number "1" and an "OK" button, and its title bar identifies it as a Word dialog box. This effect seems to have been meant to act as a generation counter, but it does not work as intended. This dialog is only shown during the initial infection of NORMAL.DOT. After the virus has managed to infect the global template, it infects all documents that are created with the "Save As" command. It is then able to spread to other systems on these documents - when a user opens an infected document on a clean system, the virus will infect the global document template. The virus consists of the following macros: AAAZAO AAAZFS AutoOpen FileSaveAs PayLoad Picture of the macro list in an infected machine Note that "AutoOpen" and "FileSaveAs" are legitimate macro names, and some users may already have attached these macros to their documents and templates. In this context, "PayLoad" sounds very ominous. It contains the text: Sub MAIN REM That's enough to prove my point End Sub However, the "PayLoad" macro is not executed at any time. You can detect the presence of the WordMacro/Concept macro virus in your system by simply selecting the command Macro from Word's Tools menu. If the macro list contains a macro named "AAAZFS" , your system is infected. You could prevent the virus from infecting your system by creating a macro named "PayLoad" that doesn't have to do anything. The virus will then consider your system already infected, and will not try to infect the global template NORMAL.DOT. This is only a temporary solution, though - somebody may modify the viruse's " AutoOpen" macro to infect the system regardless of whether NORMAL.DOT contains the macros "FileSaveAs" or "PayLoad" There is also a anti-macro virus package called WVFIX available. This package will detect if your copy of Word is infected, and will clean it if needed. It can also modify your Word settings so that this specific macro virus will be unable to infect it. In addition, WVFIX is available on the F-PROT for DOS diskette. The WVFIX package is available from the Data Fellows FTP site at URL ftp://ftp.datafellows.fi/pub/f-prot/wvfix.zip. If you are located in the United States, you might want to get the package from Command Software System's FTP site at ftp://ftp.commandcom.com/pub/fix/wvfix.zip. If you don't have F-PROT Professional which detects this virus, you can detect it manually with older F-PROT versions: you can do this by directly copying the following lines to a file called USER.DEF in your F-PROT for DOS directory: CE WordMacro/Concept 646F02690D6957573649496E7374616E63650C67 To scan for the user-defined virus string, either configure F-PROT to scan all files, or add the filename extension ".DO?" to the list of files F-PROT should scan for. It is recommended that you simply scan all files in case your users use a non-standard filename extension for their documents. Under the Targets menu item turn on User-defined Virus Strings. Isolate all documents or document templates that contain this search string and examine them for the virus. DO NOT ASSUME ANY OF THE FILES ARE INFECTED, AS THE STRINGS REQUIRED TO IDENTIFY IT COULD OCCUR IN UNINFECTED DOCUMENTS. Instead, check suspect files with the WVFIX package mentioned above. F-PROT Profesional 2.20 is able to the detect the WordMacro/Concept macro virus. WordMacro/Nuclear WordMacro/Nuclear was recently discovered. Like WordMacro/DMV and WordMacro/Concept, it spreads through Microsoft Word documents. The new virus was first spotted on a FTP site in Internet, in a publicly accessible area which has in the past been a notorious distribution site for viral code. Apparently, the viruse's distributor has some sense of irony; the virus was attached to a document which described an earlier Word macro virus, WordMacro/Concept. Whereas WordMacro/DMV is a test virus and WordMacro/Concept is only potentially harmful, WordMacro/Nuclear is destructive, harmful and generally obnoxious. It consists of a number of Word macros attached to documents. When an infected document is opened, the virus is executed and tries to infect Word's global document template, NORMAL.DOT. Unlike WordMacro/Concept - which pops up a dialogue box when it infects NORMAL.DOT - WordMacro/Nuclear does not announce its arrival in the system. Instead, it lays low and infects every document created with the "Save As" function by attaching its own macros to it. The virus tries to hide its presence by switching off the "Prompt to save NORMAL.DOT" option (in the Options dialogue, opened from Tools menu) every time a document is closed. That way, the user is no longer asked whether changes in NORMAL.DOT should be saved, and the virus is that more likely to go unnoticed. Many users relied on this option to protect themselves against the WordMacro/Concept virus, but it obviouisly no longer works against Nuclear. WordMacro/Nuclear contains several potentially destructive and irritating routines. The next time Word is started after initial infection, one of its constituent macros, "DropSuriv", looks up the time in the computer's clock. If the time is between 17.00 and 17.59, the virus tries to inject a more traditional DOS/Windows file virus called "Ph33r" into the system (as the viruse's author has commented in the viruse's code: "5PM - approx time before work is finished"). "Suriv" is, of course, "Virus" spelled backwards. However, due to an error, this routine does not work as intended in any of the popular operating environments. Another of the viruse's macros, "PayLoad", tries to delete the computer's system files IO.SYS, MSDOS.SYS and COMMAND.COM whenever the date is fifth of April. And finally, the virus adds the following two lines: And finally I would like to say: STOP ALL FRENCH NUCLEAR TESTING IN THE PACIFIC at the end of any document printed or faxed from Word during the last five seconds of any minute. Since the text is added at print- time only, the user is unlikely to notice this embarassing change. This function is handled by the viral macro "InsertPayload" The virus can be detected by selecting the Macro command from the Tools menu and checking whether the macro list contains any curiously named macros. "DropSuriv" and "InsertPayload" are obvious giveaways. F-PROT Professional 2.20 is able to the detect the WordMacro/Nuclear virus. WordMacro/Colors This macro virus was posted to a usenet newsgroup on the 14th of October, 1995. It is also known as the Rainbow virus. This macro virus infectes Word documents in a similar manner as the previous Word macro viruses, except that it does not rely only on the auto- execute macros to operate. Thus, this virus will be able to execute even if the automacros are turned off. Colors contains the following macros: AutoClose AutoExec AutoOpen FileExit FileNew FileSave FileSaveAs ToolsMacro macros All macros are encrypted with the standard Word execute-only feature. When an infected document is opened, the virus will execute when user: ˙˙˙ ˙˙˙Creates a new file ˙˙˙Closes the infected file ˙˙˙Saves the file (autosave does this automatically after the infected ˙˙˙document has been open for some time) ˙˙˙Lists macros with the Tools/Macro command It is important NOT TO USE THE TOOLS/MACRO COMMAND to check if you are infected with this virus, as you will just execute the virus while doing this. Instead, use File/Templates/Organizer/Macros command to detect and delete the offending macros. Do note that a future macro virus will probably subvert this command as well. The virus maintains a generation counter in WIN.INI, where a line "countersu =" in the [windows] part is increased during the execution of the macros. After every 300rd increments the virus will modify the system color settings; the colors of different Windows objects will be changed to random colors after next boot-up. This activation routine will not work under Microsoft Word for Macintosh. It is interesting to note that the AutoExec macro in the virus is empty. It is probably included just to overwrite an existing AutoExec macro - which might contain some antivirus routines. WordMacro/Colors also enables the automatic execution of automacros if they have been disabled, and turns off the 'prompt to save changes to NORMAL.DOT' feature, both of which have been used to fight macro viruses. WordMacro/Colors seems to be carefully written; The virus even has a debug mode built-in. The virus is probably written in Portugal. F-PROT Profesional 2.20 is not yet able to detect the WordMacro/Colors macro virus, but you can detect it manually by directly copying the following lines to a file called USER.DEF in your F-PROT for DOS directory: CE WordMacro/Colors 0100066D6163726F730100084175746F45786563 To scan for the user-defined virus string, either configure F-PROT to scan all files, or add the filename extension ".DO?" to the list of files F-PROT should scan for. It is recommended that you simply scan all files in case your users use a non-standard filename extension for their documents. Under the Targets menu item turn on User-defined Virus Strings. Isolate all documents or document templates that contain this search string and examine them for the virus. DO NOT ASSUME ANY OF THE FILES ARE INFECTED, AS THIS PRELIMINARY STRING COULD OCCUR IN UNINFECTED DOCUMENTS. F-PROT Professional 2.21 is able to the detect the WordMacro/Colors macro virus. Protecting yourself against macro viruses There is a generic way to protect your Word against currently known macro viruses except WordMacro/Colors. Select the command Macro from the Tools menu and create a new macro called "AutoExec" . Write the following commands to the macro and save it: Sub MAIN DisableAutoMacros MsgBox "AutoMacros are now turned off.", "Virus protection", 64 End Sub This macro will be executed automatically when Word starts. It will disable the feature which Concept, DMV and Nuclear use to attack the system. However, there are ways to create future macro viruses that are able to bypass such protection. Currently known Word macro viruses are not able to infect certain nationalized versions on Word. In these programs, the macro language commands have been translated to the national language, and therefore macros created with the English version of Word will not work. Since these viruses consists of macros, they will be unable to function. Description of WordMacro/Concept is based on information received from Sarah Gordon, Command Software System's F-PROT Professional Support, e-mail: sgordon@commandcom.com. There's more information on Word macro viruses and on Microsoft Word in general at Woody Leonhard's Wopr site. You might also want to check out what Microsoft has to say on the subject. --------------------------------------------------------------------- ------ Move to: ˙˙˙Newsflash! ˙˙˙Data Fellows WWW Table of Contents --------------------------------------------------------------------- ------ F-PROT-Support@DataFellows.com ... Fundies: More fun than an atheist should be legally allowed to have.

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