The V800 virus (Live after Death)
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Vesselin Bontchev reported in May 1990:
The V800 virus (Live after Death)
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I was already sending this letter, when a new virus popped up. I
haven't studied it yet. At a first glance, it has the following
properties:
- The virus infects .COM-files in a rather strange way. Large parts
of them can be found in the virus body and parts of the virus can be
found in the file (before the end of the original - non-infected -
file). It does not infect files with size less than 1024 bytes. It
seems that COMMAND.COM is never infected (there is a check for 'CO'
and 'MM' in the virus body). Sometimes the virus can attach itself
multiple times to a file. Files grow by 800 bytes after each
infection.
- Files are infected both when one executes them and when one copies
them.
- The virus is memory resident. It uses 8 K of memory. I still
cannot figure out why so much memory is needed.
- The virus is able to fetch the original INT 13h handler in PC-DOS
version 3.30. This is achieved in the same manner as in the Number
of the Beast (512) virus.
- The virus does not intercept INT 21h. Instead, it intercepts INT
2Ah, function 82h. This interrupt is called on every DOS function
call, which deals with files.
- The virus is encrypted. It seems that the encrypted part does not
change from file to file (as the Cascade virus does), but I'm not
sure.
- When the virus decrypts itself in memory, the string "Live after
Death" appears in its body. I have suspicions that this virus was
also created by the Dark Avenger.
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