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Virus Profile: WM/ERASER.H

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Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 6/1/1997
Date Added: 6/15/1997
Origin: TAIWAN
Length: Not Applicable
Type: Virus
Subtype: Macro
DAT Required: 4002
Removal Instructions
   
 
 
   

Description

This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.

Indication of Infection

On an infected system the virus hides the FILE|TEMPLATE functionality. Warning: It is important not to use this command, as you will execute the viral code. On an infected system the virus hides the TOOLS|MACRO functionality. Warning: It is important not to use this command, as you will execute the viral code.

This virus is potentially very destructive. It's primary payload is to drop the Natas.MBR virus to the user's system. It will also try to delete critical files from or format the user's C:\ drive.

When a document is opened on an infected system on October 10th, or the 16th or 7th of any month, a MessageBox that contains the text 'B52 Macro Virus' will be displayed. The virus also displays numerous other MessageBoxes which can only be understood in the taiwanese language version. These typically ask the user to answer certain questions by clicking on a button. If the user suspects that he has the virus, it is recommended that he shut down the system and reboot with a write-protected McAfee boot disk, and scan for viruses. The user should also check the AUTOEXEC.BAT and CONFIG.SYS files to make sure no dangerous modifications have been made.

Methods of Infection

General Information about Macros

Macros can be used in applications such as Word or Excel to automate complex or repetitive tasks. Once written, macros are assigned a keystroke combination, toolbar button or menu item which will activate the macro.

Macros are saved as a series of instructions in a language such as VisualBasic. Once recorded, the user can edit the macro or even add sophisticated instructions that are not normally recordable. This gives the knowledgeable user the capability to not only automate functions within the application, but to perform system functions such as deleting, renaming, or setting file attributes.

General Information about Macro Viruses

A Macro Virus uses the application's built-in power and functionality to replicate and spread. When a user receives and opens a file containing a viral macro, the viral macro will be either automatically run by opening the document or will be executed by the user by a certain key combination, a menu command, a toolbar button, etc. The viral macro will copy itself, the method depending on which application the viral macro is written for. The Macro Virus will now be present in files that the user opens, and can spread through various distribution methods. Some dangerous things a Macro Virus can do besides simply spreading could be to delete/change document contents, change settings in the Word environment, set a password, delete files, copy a DOS Virus to the user's system or insert harmful lines into the config.sys or autoexec.bat files.

Applications

Theoretically, a Macro Virus can be written for any application that stores a macro in a form that can be opened and edited using a language such as WordBasic or VisualBasic. In practice, most Macro Viruses discovered are predominantly written for Word and Excel.

Cross Platform Capability

Macro Viruses can potentially spread across different platforms such as PC to Mac, etc. Macro Viruses exist and spread within the application environment, which for macros is common among the different platform versions. Some Macro Viruses that try to do damage to a part of the user's system outside of Word will not be able to do that damage on a different machine platform. For example, a Macro Virus that tries to edit the user's Config.sys file on a PC is going to have a hard time doing the same thing on a Mac, which has no Config.sys file. So a Macro Virus that spreads and does damage on one machine could spread to another type of machine and replicate but do no damage. It is possible for a Macro Virus to figure out what kind of system its running on, and change its behavior accordingly, but this is not common.  

   

Virus Characteristics

This virus propagates by infecting Word Documents in Microsoft WORD Versions 6.x / 7.x on Windows and Macintosh platforms. The virus consists of these macros:

AUTOOPEN, FILEOPEN, FILENEW, FILECLOSE, ZLOCKMACRO, TOOLSMACRO, FILESAVEAS, FILETEMPLATES, B52,

in an infected document. The virus becomes active by using Auto- and SystemMacros. Its spreading activity remains only in the taiwanese language version of Microsoft Word. However, the virus may be able to execute its payload in another language version.

   
All Users :
Script,Batch,Macro and non memory-resident:
Use current engine and DAT files for detection and removal.

PE,Trojan,Internet Worm and memory resident :
Use specified engine and DAT files for detection. To remove, boot to MS-DOS mode or use a boot diskette and use the command line scanner:

SCANPM /ADL /CLEAN /ALL

Additional Windows ME/XP removal considerations


Users should not trust file icons, particularly when receiving files from others via P2P clients, IRC, email or other mediums where users can share files.

AVERT Recommended Updates :

* Office2000 Updates

* Malformed Word Document Could Enable Macro to Run Automatically (Information/Patch )

* scriptlet.typelib/Eyedog vulnerability patch

* Outlook as an email attachment security update

* Exchange 5.5 post SP3 Information Store Patch 5.5.2652.42 - this patch corrects detection issues with GroupShield

For a list of attachments blocked by the Outlook patch and a general FAQ, visit this link .
Additionally, Network Administrators can configure this update using an available tool - visit this link for more information .

It is very common for macro viruses to disable options within Office applications for example in Word, the macro protection warning commonly is disabled. After cleaning macro viruses, ensure that your previously set options are again enabled.