F-Secure Virus Descriptions : Teocatl

This macro virus infects Office97 Word documents and Excel sheets. It is the second known macro virus that is able to infect several MS Office applications (first was Cross).

The code of virus is placed in one module named StrangeDays and contains eight functions. Some of these start automatically under Word (AutoOpen), others start automatically under Excel (Auto_Open).

The virus spreads within applications (Word to Word, Excel to Excel) as well as drops infected files to another application (Word to Excel and Excel to Word).

The virus uses the same VBA program code under both Word and Excel.

The virus uses Import/Export VisualBasic functions: the virus exports its Basic code to the C:\LO.SYS file, and then imports it into documents.

To spread from Word to Excel and vice versa, the virus uses a trick with auto-loading ability of Word and Excel. These applications load templates (Word) and sheets (Excel) from startup directory: to infect Word from Excel the virus creates new NORMAL.DOT (Word) and PERSONAL.XLS (Excel) files in startup directory.

NORMAL.DOT and PERSONAL.XLS contain a small loader program. This loader imports the actualy virus code from the C:\LO.SYS file to NORMAL.DOT or PERSONAL.XLS, depending on the platform.

The virus disables the Tools/Macro, Tools/Options, File/Templates and View/VBCode menu items as well as turns off VisualBasicEditor and VirusProtection. This is done in order to protect the virus from being analyzed. The virus also changes VirusProtection instructions in the system registry.

On 26th of any month, Teocatl displays a dialog box and deletes all files in the current directory. The following text is displayed:

        Strange Days by Reptile/29A
        Strange days have found us
        Strange days have tracked us down
        They're going to destroy...