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
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.Read more
Platform: MSExcel
Microsoft Excel (MS Excel) is a popular spreadsheet program and part of the Microsoft Office productivity suite. Excel files have .xls or .xlsx extensions.Description
Technical Details
This virus infects Excel sheets. It contains only one module (macro). This module has the name containing 11 spaces and is invisible in system - menu Microsoft Excel Tools/Macros does not show any macros. The virus module has four functions: Auto_Open, Auto_Range, Current_Open, Auto_Close.
While opening an infected file the virus function Auto_Open takes control. This function "renames" Excel - the title "Microsoft Excel" is replaced with "Microsofa Excel". This function then infects the system. To do that it looks for BOOK.XLT file in Startup Path. If there is no such file (the system is not infected), the virus displays:
Microsoft Excel has detected a corrupted add-in file. Click 'OK' to repair this file.Not depending on user's reply, the virus creates there the BOOK.XLT file containing virus code. After infecting the virus displays:
File successfully repaired!While loading into the system Excel loads all XLT files (including infected BOOK.XLT) from Startup Path, and as a result the virus takes control as far as Excel is loading. The virus then sets its function Auto_Range for system function OnSheetActivate. On any sheet activation this function takes control and infects the active file, if it is not infected yet.
The virus does not allow to unload itself from the system - while closing any file the virus sets the system function OnWindow to its function Auto_Range. As a result the virus re-installs itself while opening any file.
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