HPAVC/HPAVC CD-ROM.iso/pc/MVUPDAT3.ZIP/MACRO_AV.ZIP/MACRO008.TXT

Text File | 1996-09-02 | 27.2 KB | 646 lines

Microsoft Word document macro viruses

Date: 23rd of August, 1995, updated 16th of July 1996.

   * Introduction
   * WordMacro/DMV
   * WordMacro/Concept
   * WordMacro/Nuclear
   * WordMacro/Colors
   * WordMacro/Hot
   * WordMacro/Atom
   * Other Word macro viruses and trojans
   * Protecting yourself against Word macro viruses
   * F-PROT and Word macro viruses
   * Downloading F-MACRO utility

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 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 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 File/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

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".

Concept replicates only on English versions of Word. However, one
translated version to operate on French Word has been found. This variant
is known as WordMacro/Concept.Fr.

F-PROT Profesional 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 File/Save
As command 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. This attempt will fail due a programming error (virus authors
never test drive the destructive parts of their code, it seems). 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 Professional 2.21 is able to the detect the WordMacro/Colors macro
virus.

WordMacro/Hot

WordMacro/Hot was the first Word macro virus written in Russia. It was
found in the wild over there in January 1996.

Hot spreads in a similar manner as the WordMacro/Concept virus: when an
infected DOC is first opened, virus modifies the NORMAL.DOT file, and will
spread to other documents after that.

Unlike the earlier Word macro viruses, Hot does not replicate with the
File/Save As command - it infects only during the basic File/Save command.
This means that Hot will infect only existing documents in the system - not
new ones.

Infected documents contain the following four macros, which are visible in
the macro list:

   * AutoOpen
   * DrawBringInFrOut
   * InsertPBreak
   * ToolsRepaginat

When Hot infects NORMAL.DOT, it renames these macros to:

   * StartOfDoc
   * AutoOpen
   * InsertPageBreak
   * FileSave

Macros have been saved with the 'execute-only' feature, which means that a
user can't view or edit them.

WordMacro/Hot contains a counter. It adds a line like this to the
WINWORD6.INI file:

        QLHot=35112

This number is based on the number of days during this century. Hot adds 14
to this number and then waits until this latency time of 14 days has
passed. Hot will spread normally during this time, it will just not
activate.

After the 14 day pause, there is a 1 in 7 chance that a document will be
erased when it is opened. Virus will delete all text and re-save the
document. Hot does not do this, if it find a file called EGA5.CPI from the
C:\DOS directory. A comment in the source code of the virus hints that this
feature is added so that the author of the virus and his friends can
protect themselves from the activation damage:

  '---------------------------------------------------------------
  '- Main danger section: if TodayNo=(QLHotDateNo + RndDateNo) ---
  '- and if File C:DOSega5.cpi not exist (not for OUR friends) -
  '---------------------------------------------------------------

By default, there is no file by the name EGA5.CPI in MS-DOS distributions.

WordMacro/Hot was the first macro virus to use external functions. This
system allows Word macros to call any standard Windows API call. The use of
external functions is specific to Windows 3.1x means that WordMacro/Hot
will be unable to spread under Word for Macintosh or Word 7 for Windows 95:
opening an infected document will just produce an error message.

F-PROT Professional 2.21a is able to detect the WordMacro/Hot virus.

WordMacro/Atom

WordMacro/Atom was found in February 1996. It's operating mechanism is
quite similar to WordMacro/Concept, with the following differences:

   * All the macros in this virus are encrypted (Word's execute-only
     feature)
   * The virus replicates during file openings as well, in addition to
     saving files
   * The virus has two destructive payloads

First activation happens when the date is December 13th. At this date the
virus attempts to delete all files in the current directory.

Second activation happens when a File/Save As command is issued and
the seconds of the clock are equal to 13. If so, the virus will
password-protect the document, making it unaccesible to the user in the
future. The password is set to be ATOM#1.

It is not easy to give a search string for this virus: some of the
replicants are usually in files password-protected by the virus, and thus
contain no constant user-definable search string.

Disabling automacros will make Atom unable to execute and spread. Turning
on the Prompt to save NORMAL.DOT setting will make Atom unable to infect
NORMAL.DOT, but it will still be able to infect documents that are opened
or saved during the same Word session.

WordMacro/Atom is not known to be in the wild.

Other Word macro viruses and trojans

In total the following macro viruses have been found between August 1995
and June 1996:

WordMacro/Atom
WordMacro/Boom
WordMacro/Colors.A
WordMacro/Colors.B
WordMacro/Concept.A
WordMacro/Concept.B
WordMacro/Concept.C
WordMacro/Concept.D
WordMacro/Date
WordMacro/Divina
WordMacro/DMV
WordMacro/Doggie
WordMacro/Friendly
WordMacro/GoldFish
WordMacro/Guess
WordMacro/Hot
WordMacro/Imposter
WordMacro/Irish
WordMacro/KillDLL
WordMacro/LBYNJ
WordMacro/MDMA
WordMacro/NOP
WordMacro/Nuclear.A
WordMacro/Nuclear.B
WordMacro/PCW
WordMacro/Pheeew
WordMacro/Polite
WordMacro/Reflex
WordMacro/Wazzu
WordMacro/Xenixos

WordMacro/Wazzu consists of a single AutoOpen macro; this makes it language
independent, ie. this macro virus is able to infect localized versions of
Word as well as the english Word.

Unlike most other macro viruses, Wazzu has really been seen in the wild:
there are few reports of infections in USA during spring 1996.

Wazzu modifies the contents of documents it infects, moving words around
and inserting the text 'wazzu '. Word Wazzu is reported to be a nickname
for the Washington State University.

There exists also several trojans written in the Word macro language. These
typically delete data as soon as the trojanized document is open. Since
these do not spread by themselves, they are not widespread and not
considered to be a significant threat.

Some known macro trojans are WordTrojan/FormatC and
WordTrojan/WeideroffnenC. F-PROT does not attempt to search for macro
trojans and we have no plans to add support for them.

Protecting yourself against Word macro viruses

There is a generic way to protect your Word against some of the known macro
viruses. However, this should not be relied on alone, as it can not stop
even all known macro viruses. 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 viruses like Concept, DMV and Nuclear use to attack the
system. However, there are ways to create macro viruses that are able to
bypass such protection.

Only some of currently known Word macro viruses are able to infect
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. However,
viruses like DMV or Wazzu are able to spread in any version of Word.

F-PROT and Word macro viruses

F-PROT has been able to detect Word macro viruses since October 1995.
Here's a history of the detected viruses in different F-PROT version (only
bimonthly updates listed):

F-PROT 2.20, October 1995:

WordMacro/Concept
WordMacro/DMV
WordMacro/Nuclear

F-PROT 2.21, December 1995:

WordMacro/DMV
WordMacro/Colors
WordMacro/Concept
WordMacro/Nuclear

F-PROT 2.22, March 1996:

WordMacro/Atom
WordMacro/Colors
WordMacro/Concept
WordMacro/DMV
WordMacro/Hot
WordMacro/Imposter
WordMacro/Nuclear.A
WordMacro/Nuclear.B
WordMacro/Xenixos

F-PROT 2.23, May 1996:

WordMacro/Atom
WordMacro/Boom
WordMacro/Colors
WordMacro/Concept
WordMacro/DMV
WordMacro/Friendly
WordMacro/Hot
WordMacro/Imposter
WordMacro/Lbynj
WordMacro/Nop
WordMacro/Nuclear.A
WordMacro/Nuclear.B
WordMacro/Pheew
WordMacro/Wazzu
WordMacro/Xenixos

Unlike the limited free version of F-PROT, F-PROT Professional is able to
disinfect macro viruses automatically.

This scanning and disinfection technology was developed by Data Fellows
Ltd. F-PROT Professional for Windows, Windows 95, Windows NT and OS/2 as
well as the realtime Windows VxD scanners have these macro scanning
features built in to their normal scanners.

If you are running a VxD-based background protection from the F-PROT
Professional suite, you will be notified on infected document files as soon
as you try to open or copy them or when you are receiving such a document
as an e-mail attachment or downloading it from www. Disinfection can also
be done in realtime. A VxD-based solution provides significantly better
protection than antivirus systems relying on the Word macro language.

Downloading F-MACRO utility

F-MACRO is a stand-alone DOS application, which is based on the F-PROT
Professional scanning technology. It is able to disinfect macro viruses
known to it. F-MACRO can be downloaded from our ftp site.
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Microsoft Excel macro viruses

Date: 16th of July 1996, updated 26th of July 1996

A year after the first widespread Microsoft Word macro virus, the first
real Microsoft Excel macro was found in July 1996. Word macro viruses have
demonstrated that viruses spreading in macro format inside document files
can spread far and wide: WordMacro/Concept is the most commonly reported
virus in the world. The first Excel macro virus was named
ExcelMacro/Laroux.

Once the Excel environment has been infected by this virus, the virus will
always be active when Excel is loaded and will infect any new Excel
workbooks that are created as well as old workbooks when they are accessed.
The virus spreads from a machine to another when XLS files are exchanged
over a local network, over the internet, in e-mail or on diskettes.

ExcelMacro/Laroux was written in Visual Basic for Applications (VBA). This
is a macro language based on the Visual Basic language from Microsoft. This
virus is be able to operate under Excel 5.x and 7.x under Windows 3.x,
Windows 95 and Windows NT. This virus does not work under any version of
Excel for Macintosh or Excel 3.x or 4.x for Windows. It also fails under
some localized versions of Excel, but works fine under other (for example,
it won't work under French Excel, but replicates fine under Finnish Excel).
This depends on how the translation is done.

ExcelMacro/Laroux consists of two macros, auto_open and check_files. The
auto_open macro executes whenever an infected Spreadsheet is opened,
followed by the check_files macro which determines the startup path of
Excel. If there is no file named PERSONAL.XLS in the startup path, the
virus creates one. This file contains a module called "laroux".

PERSONAL.XLS is the default filename for any macros recorded under Excel.
Thus you might have PERSONAL.XLS on your system even though you are not
infected by this virus. The startup path is by default set as
\MSOFFICE\EXCEL\XLSTART, but it can be changed from Excel's
Tools/Options/General/Alternate Startup File menu option.

If an infected workbook resides on a write-protected floppy, an error will
occur when Excel tries to open it and the virus will not be able to
replicate.

ExcelMacro/Laroux is not intentionally destructive and contains no payload;
it just replicates.

Detecting ExcelMacro/Laroux with F-PROT Professional

F-PROT supports user defined search strings to search for new viruses. Add
the following search string with the name ExcelMacro/Laroux:

        00 21 00 60 00 27 20 6A 00 20 20 6A 00 AD 00 01 00 5C 00 11

After this, check all Excel worksheets for infection. You can do this by
scanning all files or by adding XL? extension to the list of file
extensions to be scanned.

Infected files will be reported by F-PROT like this:

        C:\SHEETS\CUSTOMER.XLS contains the ExcelMacro/Laroux search string.

Detecting ExcelMacro/Laroux manually

Select Tools/Macro from Excel menus. If you find the macros auto_open,
check_files, PERSONAL.XLS!auto_open and PERSONAL.XLS!check_files (and
possibly 'bookname'!auto_open and 'bookname'!check_files from any infected
workbook you have open), infection is likely. Re-check this by selecting
the Window/Unhide menu and unhide the Personal file. This should make the
Personal sheet visible, with text laroux in in the sheet tab.

To disinfect Laroux, delete these macros and exit Excel, saving all
changes. Now Excel itself is clean. Next, open all infected workbooks one
by one, keeping the left shift pressed down while opening them (according
to Excel documentation, this bypasses automacros, but unfortunately it
doesn't seem to always work). Then open Tools/Macro and delete the virus
macros and re-save the file.

We're trying to evaluate how widely this virus has spread; If you find you
are infected with this virus, please contact us.

Future

It can be expected that virus scanners won't be instantly updated to handle
Excel macro viruses - Excel uses a propriaty file format, and proper
scanning and disinfection of Excel files will need co-operation from
Microsoft. From our experiences with the Word file format information
exchange, this can take some time.

In general, Microsoft Excel has even more powerful set of commands and
system hooks than Microsoft Word. This means that Excel viruses have more
ways to propogate than Word viruses (or Ami Pro viruses). However, Excel is
not as widely used as Word.

What about DMV?

A person called Joel McNamara wrote a Word macro virus called WordMacro/DMV
to study the behavior of macro viruses in fall 1994 - at the same time, he
published a detailed study about macro viruses.

McNamara also published a skeleton for a virus to infect Microsoft Excel
spreadsheet files. However, this file was not functional and was not able
to spread. So, at it's current state, it can not be called a virus. It
would be possible to develop a working virus from the DMV Excel sample, but
we have not seen such yet. This makes ExcelMacro/Laroux the first working
Excel virus we've seen.

Although it can be argued that spreading information like Mr. McNamara has
done 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 it. We oppose to such behaviour.

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Ami Pro macro viruses

Date: 23rd of January, 1996, updated 27th of January.

With Microsoft Word, a document and all macros related to it are stored in
a single file. So a file called DOCUMENT.DOC or DOCUMENT.DOT contains both
the document contents and the macros. But with Lotus' Ami Pro, macros are
stored in a separate file: if you have DOCUMENT.SAM, macros related to it
are in DOCUMENT.SMM. This makes it somewhat more difficult for Ami Pro
viruses to spread, since when a user is distributing a document, he is
likely to leave the .SMM file behind, effectively disabling the virus.

The first Ami Pro macro virus was located in January 1996. The virus, which
is called Green Stripe or AmiMacro/GreenStripe, works by creating a .SMM
file for every .SAM file in Ami Pro's default DOCS directory
(\amipro\docs), and modifying the existing .SAM files to use the new
macros. The name of the virus comes from it's main macro procedure, which
is called Green_Stripe_virus.

Green Stripe propagates by intercepting Ami's File/Save and File/Save As
commands. Using File/Save As and saving an infected document to a network
drive or a floppy is the only likely way for this virus to spread from a
machine to another.

Green Stripe has an activation routine which triggers during saving: the
virus searches through the document and replaces all occurences of the word
"its" with "it's". Such a change can easily go undetected by the user.
However, it is unclear whether this routine works at all.

Green Stripe is rumoured to have been originally published in a US
virus-related magazine. It is unlikely to spread in the wild.

Detecting Green Stripe

Open the Tools/Macros/Edit menu and check whether the document has a .SMM
macro file assigned to be executed on open. To disinfect an infected
document, just delete the .SMM file, open the document to Ami and uncheck
the above setting.

Also, the initial infection process takes a long time, and the user is
likely to notice that something is going wrong, since all the documents in
the default directory are quickly appearing and disappearing on the screen
while the virus infects them.

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