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 it creates a file: PERSONAL.XLM in the Startup path of MS EXCEL. When opening infected files this virus will delete attempt to delete files in specific directories for antivirus products. If the current date is the 1st, 9th or 23rd , this virus will modify the AUTOEXEC.BAT file with an instruction to format the hard drive. If the current hour is the 1st or if the current minute is the 1st the payload is to begin numerous text files to the hard drive, until there is no more space left. .
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.
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.