Virus.MSWord.Class

Parent class: VirWare

Viruses and worms are malicious programs that self-replicate on computers or via computer networks without the user being aware; each subsequent copy of such malicious programs is also able to self-replicate. Malicious programs which spread via networks or infect remote machines when commanded to do so by the “owner” (e.g. Backdoors) or programs that create multiple copies that are unable to self-replicate are not part of the Viruses and Worms subclass. The main characteristic used to determine whether or not a program is classified as a separate behaviour within the Viruses and Worms subclass is how the program propagates (i.e. how the malicious program spreads copies of itself via local or network resources.) Most known worms are spread as files sent as email attachments, via a link to a web or FTP resource, via a link sent in an ICQ or IRC message, via P2P file sharing networks etc. Some worms spread as network packets; these directly penetrate the computer memory, and the worm code is then activated. Worms use the following techniques to penetrate remote computers and launch copies of themselves: social engineering (for example, an email message suggesting the user opens an attached file), exploiting network configuration errors (such as copying to a fully accessible disk), and exploiting loopholes in operating system and application security. Viruses can be divided in accordance with the method used to infect a computer:

• file viruses
• boot sector viruses
• macro viruses
• script viruses

Any program within this subclass can have additional Trojan functions. It should also be noted that many worms use more than one method in order to spread copies via networks.

Class: Virus

Viruses replicate on the resources of the local machine. Unlike worms, viruses do not use network services to propagate or penetrate other computers. A copy of a virus will reach remote computers only if the infected object is, for some reason unrelated to the virus function, activated on another computer. For example: when infecting accessible disks, a virus penetrates a file located on a network resource a virus copies itself to a removable storage device or infects a file on a removable device a user sends an email with an infected attachment.

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Platform: MSWord

Microsoft Word (MS Word) is a popular word processor and part of Microsoft Office. Microsoft Word files have a .doc or .docx extension.

Description

Technical Details

This virus contains two macros in one Module, "ThisDocument," and the macros have different names in documents and NORMAL.DOT:

Documents         NORMAL.DOT



AutoOpen          AutoClose   - infection and trigger routines



ViewVBCode        ToolsMacro  - stealth, disables viewing macro code

The virus infects the global macros area upon the opening of an infected document. While infecting, the virus exports virus code to the C:CLASS.SYS and inserts it into NORMAL.DOT. Documents are infected in the same way.

The virus mutation (polymorphic) routine inserts comments into virus code, containing a user name, current date and time, and information about the active printer.

The virus uses an effective way to hide its code. By using special WordBasic operators, the virus installs its module, not into the standard area of macro programs, but into the area of Word classes - the area of standard routines that handle Word events, i.e., Word kernel. The virus appends its code to documents and templates, not as a user application (macro program), but as a "native" Word component. As a result, the virus is not visible in Tools/Macro and File/Templates (for what reason does the virus then hook ToolsMacro?)

The virus disables the AutoProtection. On the 31st, the virus displays the MessageBox:

This Is Class



?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?



?      VicodinES     /CB    /TNN      ?



?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?-?

Class.d

Each month from June until December on day 14, the virus displays the message:

Class.Poppy



I think  is a big stupid jerk!

The virus also changes values in the registry keys:

HKLMSoftwareMicrosoftWindowsCurrentVersionRegisteredOwner = "VicodinES /CB /TNN"



RegisteredOrganization = "-(Dr. Diet Mountain Dew)-"

Class.bs

Upon infection, this virus modifies the system registry by writing "Clazz" as the registered owner of this Windows copy. Upon trying to view, the virus codes it with a probability of 25% and sets the "Clazz" password for active document, or, with the same probability, deletes all files in the current folder.

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