mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-24 20:35:25 +00:00
59 lines
1.4 KiB
NASM
59 lines
1.4 KiB
NASM
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SEG_A segment byte public
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assume cs:seg_a,ds:seg_a
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org 100h
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MULTIPLEXOR proc far
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start:
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jmp BEGIN
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MULTIPLEXOR endp
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; Subroutine work on the DOS Int2Fh (Multiplexor)
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; It stay rezident and calling Old Int2Fh, if don't call FnBAh.
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; Functions (ah=BAh): <20> Return:
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; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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; al=0 <20> al=0ffh, bl=READ_ON
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; al=1 <20> bl=READ_ON=1
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; al=2 <20> bl=READ_ON=0
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; al=3 <20> Calling WRITE; bl=READ_ON=1
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ADM proc
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cmp ah,byte ptr cs:ADM_INT
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je ADM_WORK
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db 0eah
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INT2F_JUMP db 0,0,0b2h,89h
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ADM_WORK:
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cmp al,0
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jne ADM_WORK1
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mov al,0ffh
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IRET
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ADM_WORK1:
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push dx
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push ax
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mov dl,al
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mov ah,2
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int 21h
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pop ax
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pop dx
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IRET
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ADM endp
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ADM_INT db 93h
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REZIDENT:
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BEGIN:
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; Init interrupt vectors
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mov ax,352fh
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int 21h
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mov word ptr cs:INT2F_JUMP,bx
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mov word ptr cs:INT2F_JUMP+2,es
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mov al,2fh
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mov dx,offset ADM
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mov ah,25h
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int 21h
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mov ah,093h
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mov al,'*'
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int 2fh
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mov dx,offset REZIDENT
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int 27h
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SEG_A ends
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end start
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