Virus Database

Macro.Excel97.Tracker-based

Description Macro.Excel97.Tracker-based

This is a harmless macro-virus. It infects MS Excel 97/2000 workbooks upon their closing or saving with a new name. The virus disables the MS Excel97 macro-virus protection using direct registry access. In the Excel start-up folder, the virus creates the infected file "Base5874.xls".
Upon infecting every new computer, the virus saves, in document volume, the ID of the drive where Excel is installed. It stores drive IDs as documents custom properties. On tab File->Properties->Custom in the properties list are shown all IDs that the virus stores from moment it was created. All IDs begin with "IVID".
The virus has no payload routines.

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Drepo.2461

Description Drepo.2461

These are not dangerous memory resident encrypted parasitic viruses. While executing an infected EXE file the virus reads the root directory of C: drive by using INT 25h direct read call, searches there for the "COMMAND COM" string in the read buffer, replaces that string with "COMMAND LOM", clears the file attribute field, and saves the result to the disk by using direct write INT 26h call. Then the virus opens the C:COMMAND.LOM file (ex-COMMAND.COM), encrypts and writes itself to the end of the file to the COMMAND.COM stack area (the file length does not grow, see "Lehigh"), and then overwrites the file entry point (the code that is pointed by JMP instruction at the file beginning) with 2Eh bytes of a decryption routine. Then the virus restores the original contents of the root directory (also by using INT 26h call) and returns the control to the host EXE file. I see that such complex way to infect the file is to avoid memory resident anti-virus monitors.
While executing the infected COMMAND.COM the virus hooks INT 21h, stays memory resident and writes itself to the end of EXE files that are opened or closed. When the archivator ARJ.EXE or RAR.EXE is executed, the virus reserves an extra block of the memory to infect the files that are compressed or extracted from an archive.
The virus also hooks INT 9 (keyboard) and two month after infecting a system, depending on the keys that are pressed, it beeps by the PC speaker.
The virus contains the text strings:
ARJ.EXE RAR.EXE
C:COMMAND COM
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Shareware version.
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Drizzle.1600

Description Drizzle.1600

It is a dangerous memory resident parasitic virus. It hooks INT 16h, 21h and writes itself to the end of .COM files (except COMMAND.COM) that are executed. The virus runs a counter in the MBR of the hard drive and increases this counter on each installation into the memory and on each infection. When counter reaches 400h (1024) the virus corrupts the MBR code, and it will halt the system on next booting. When this counter reaches 256, the virus starts to change keys that are entered (INT 16h) and delays on any keystroke. The virus contains the only text string:
COMMAND.COM

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